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WO1998017695A1 - Compounds and methods - Google Patents

Compounds and methods Download PDF

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Publication number
WO1998017695A1
WO1998017695A1 PCT/US1997/019450 US9719450W WO9817695A1 WO 1998017695 A1 WO1998017695 A1 WO 1998017695A1 US 9719450 W US9719450 W US 9719450W WO 9817695 A1 WO9817695 A1 WO 9817695A1
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WO
WIPO (PCT)
Prior art keywords
scheme
resin
bound
alkyl
compounds
Prior art date
Application number
PCT/US1997/019450
Other languages
French (fr)
Inventor
Balan Chenera
Original Assignee
Smithkline Beecham Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GB939325621A external-priority patent/GB9325621D0/en
Priority claimed from US08/663,148 external-priority patent/US5773512A/en
Priority claimed from PCT/US1994/014414 external-priority patent/WO1995016712A1/en
Application filed by Smithkline Beecham Corporation filed Critical Smithkline Beecham Corporation
Priority to EP97947288A priority Critical patent/EP0934345A4/en
Priority to JP10519697A priority patent/JP2001502354A/en
Priority to CA002269737A priority patent/CA2269737A1/en
Publication of WO1998017695A1 publication Critical patent/WO1998017695A1/en

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F8/00—Chemical modification by after-treatment
    • C08F8/42—Introducing metal atoms or metal-containing groups
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00274—Sequential or parallel reactions; Apparatus and devices for combinatorial chemistry or for making arrays; Chemical library technology
    • B01J2219/00277—Apparatus
    • B01J2219/00497—Features relating to the solid phase supports

Definitions

  • the standard method for conducting a search is to screen a variety of pre-existing chemical moieties, for example, naturally occurring compounds or compounds which exist in synthetic libraries or databanks.
  • the biological activity of the pre-existing chemical moieties is determined by applying the moieties to an assay which has been designed to test a particular property of the chemical moiety being screened, for example, a receptor binding assay which tests the ability of the moiety to bind to a particular receptor site.
  • an assay which has been designed to test a particular property of the chemical moiety being screened, for example, a receptor binding assay which tests the ability of the moiety to bind to a particular receptor site.
  • silicon-based polymer resins are useful in the preparation of a single compound, e.g., an aromatic carbocycle, or a library of molecularly diverse compounds which are aromatic carbocycles, each comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said aromatic carbons having a hydrogen, halogen, hydroxy or acyloxy group bound to them after cleavage from the resin.
  • non-peptide compounds each comprised of a core structure, bind to a variety of receptors, in particular, G-protein coupled receptors.
  • the core structures including aromatic carbocycles, may be used as templates for developing libraries of non- peptide compounds which are analogs of the core structures. Therefore, rather than synthesizing individual analogs of these non-peptide compounds for screening, large numbers of non-peptide compounds which may be receptor ligands, in particular G- protein coupled receptor ligands, can be synthesized by the combinatorial methods described herein and screened in assays developed for determining lead compounds as pharmaceutical agents.
  • the methods disclosed herein may also be applied to obtain libraries of compounds, including aromatci carbocycles, that are enzyme inhibitors, receptor ligands or channel blockers.
  • the present invention is directed to non-peptide compounds, each comprised of a core structure.
  • the present invention is also directed to the use of these core structures as templates for developing libraries of non-peptide compounds which are analogs of the core structures.
  • this invention is directed to libraries of compounds which comprise receptor ligands, in particular, G-protein coupled receptor ligands, enzyme inhibitors and channel blockers and the combinatorial synthetic methods for making such libraries of compounds.
  • receptor ligands in particular, G-protein coupled receptor ligands, enzyme inhibitors and channel blockers and the combinatorial synthetic methods for making such libraries of compounds.
  • this invention relates to novel silicon-based polymer resins, methods for preparing said resins and intermediates used in the preparation of said resins.
  • one aspect of this invention relates to methods for preparing one or a plurality of derivatized compounds by resin-bound synthesis, wherein the compounds are aromatic carbocycles each comprising an aromatic carbon atom and at least one substituent X, A, B or C that is not hydrogen or alkyl, said aromatic carbons having a hydrogen, halogen, hydroxy or acyloxy group bound to them after cleavage from the resin.
  • this aspect of the invention relates to methods for utilizing silicon chemistry to effectuate the cleavage of an aromatic carbocycle from a polymer resin while leaving a hydrogen, halogen, hydroxy or acyloxy group on the aromatic carbocycle at the cleavage position.
  • the present invention is directed to methods for screening a compound or plurality of compounds made according to the synthetic methods disclosed herein, which comprise using the compounds in suitable assays developed for detecting the compounds' utility as pharmaceutical agents.
  • this invention relates to a method of screening G-protein coupled receptors with ligands that are known to bind other G-protein coupled receptors, or that are related to ligands that are known to bind other G- protein coupled receptors.
  • core structure(s) is used herein at all occurrences to mean a core molecular structure(s) which is derived from compounds which have been shown to interact with a receptor, in particular, a G-protein coupled receptor, and which is used as a template for designing the libraries of compounds to be made.
  • Core structures may be aromatic carbocycles as defined below.
  • library of compounds is used herein at all occurrences to mean a series or plurality of compounds derivatized from their core structure.
  • the core structure used for designing a library of compounds is an aromatic carbocycle.
  • combinatorial library is used herein at all occurrences to mean a collection of compounds based upon a core structure, for example, an aromatic carbocycle structure, wherein the library contains a discrete number of independently variable substituents, functional groups or structural elements, and further, wherein the library is designed so that, for the range of chemical moieties selected for each of the independently variable substituents, compounds containing all possible permutations of those substituents will be present in the library.
  • a core structure labeled R
  • X is taken from m different chemical moieties
  • Y from n different chemical moieties
  • Z from p different chemical moieties
  • m, n and p are integers which define the size of the library, and which range between 1 to 1000; preferably between 1 to 100; most preferably between 1 to 20
  • the library would contain m x n xp different chemical compounds and all possible combinations of X, Y and Z would be present on the core structure R within that library.
  • the methods for preparing combinatorial libraries of compounds are such that the molecularly diverse compound members of the libraries are synthesized simultaneously.
  • aromatic carbocycle is used herein at all occurrences to mean a compound which comprises a single ring or a fused ring system, preferably 5-14 membered ring systems, and, for purposes herein, includes an optionally substituted biphenyl, composed of carbon atoms having aromatic character, e.g., characterized by delocalized electron resonance and the ability to sustain a ring current and which ring or ring systems may include one or more heteroatoms selected from oxygen, nitrogen or sulfur.
  • the aromatic carbocycle may be optionally substituted by one or more substituents herein described as "substituent X", "substituent A", “substituent B” or "substituent C".
  • the aromatic carbocycle is a biphenyl
  • the substituents X, A, B or C may be, independently, on one or both rings. This is similarly so for other aromatic carbocyclic rings or ring systems as defined above. It will be recognized by the skilled artisan that a large number of aromatic carbocycles may be made using the silane linkers of this invention, provided that the chemistry used to prepare the aromatic carbocycles is compatible with the aryl silane bond, defined below.
  • Suitable aromatic carbocycles include, but are not limited to, optionally substituted phenyl rings, optionally substituted naphthyl rings, optionally substituted tetrahydronaphthyl rings, optionally substituted anthracenyl rings, optionally substituted 1-, 2- or 3- tetrahydrobenzazepines; optionally substituted 1,4-, 1,5-, or 2,4- tetrahydrobenzodiazepines; optionally substituted biphenyl tetrazoles; optionally substituted 1,3- or 1,4-diaminobenzene compounds; or optionally substituted 1,3- or 1,4-aminocarboxyphenyl compounds.
  • the aromatic carbocycles described herein may serve as core structures, and therefore, as templates for designing libraries of compounds to be screened as pharmaceutical agents.
  • the aromatic carbocycles are G-protein coupled receptor ligands, channel blockers and/or enzyme inhibitors.
  • reaction-bound synthesis and “solid phase synthesis” are used herein interchangeably to mean one or a series of chemical reactions used to prepare either a single compound or a library of molecularly diverse compounds, wherein the chemical reactions are performed on a compound, suitably, an aromatic carbocycle, which is bound to a polymeric resin support through an appropriate linkage, suitably, an silane linker.
  • resin inert resin
  • polymeric resin polymeric resin support
  • bead or other solid support such as beads, pellets, disks, capillaries, hollow fibers, needles, solid fibers, cellulose beads, pore-glass beads, silica gels, grafted co-poly beads, poly-acrylamide beads, latex beads, dimethylacrylamide beads optionally cross-linked with N,N'-bis- acryloyl ethylene diamine, glass particles coated with a hydrophobic polymer, etc., i.e., a material having a rigid or semi-rigid surface.
  • the solid support is suitably made of, for example, cross linked polystyrene resin, polyethylene glycol- polystyrene resin, benzyl ester resins or benzhydrylamine resins and any other substance which may be used as such and which would be known or obvious to one of ordinary skill in the art.
  • the linker to the resin is silicon-based, the above terms mean any aliphatic or aromatic polymer which lacks functionality known to participate in the additional synthetic chemistry for generation of the derivatized compounds of this invention, and which is stable to conditions for protodesilylation.
  • Preferred polymer resins for use herein are the Merrifield resin (available commercially from Nova Biochem) and the Wang resin (synthesis described below).
  • the compounds (or libraries of compounds) made by the instant methods may either remain bound to the resin which is used to perform the resin-bound synthesis (hereinafter referred to as "resin-bound compounds (or libraries)”) or not bound to a resin (hereinafter referred to as “soluble compounds (or libraries)").
  • silane linker or “silane linker group” are used herein at all occurrences to mean the moiety which binds the aromatic carbocycle to the polymeric resin support, which linker comprises a silicon atom bound to an alkyl chain comprising one or more methylene groups, said alkyl chain optionally having one or more intervening heteroatoms and/or aryl groups, or combinations thereof.
  • Suitable silane linkers for use in this invention comprise a moiety of the following formula: -D-CH 2 -Si-R"R'", wherein R" and R'" are independently, Ci to C alkyl, and D is a C j to C20 alkyl chain optionally having one or more intervening heteroatoms and/or optionally substituted aryl groups. It will be recognized that the alkyl chain may contain both intervening heteroatoms and intervening optionally substituted aryl groups.
  • R" and R" are independently, C to C4 alkyl, more preferably, R" and R"' are both methyl or ethyl, more preferably methyl.
  • aryl silane compound is used herein at all occurrences to mean an intermediate compound comprising an aromatic carbocycle having an aromatic carbon and at least one substituent X, A, B or C that is not hydrogen or alkyl, wherein the aromatic carbon is bound to a silane linker through an aryl silane bond.
  • an aryl silane compound within the scope of this invention is defined by a compound of Formula (LB).
  • aryl silane bond is used herein at all occurrences to mean the bond between the aromatic carbon of an aromatic carbocycle and the silicon atom of a silane linker.
  • this bond is cleaved in order to decouple the aromatic carbocycle from the resin-bound aryl silane intermediate.
  • resin-bound aryl silane intermediate is used herein at all occurrences to mean an intermediate wherein an aromatic carbocycle is directly bound to a silane linker, which linker is directly bound to a polymeric resin support. Therefore, it will be recognized that a resin-bound aryl silane intermediate is a moiety which couples an aromatic carbocycle to a polymeric resin support through a silane linker.
  • C are used herein at all occurrences to mean a non-nucleophilic substituent, including, but not limited to, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether (e.g., -alkyl-S -alkyl-), alkylthio (e.g., alkyl-SH), C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyamino-carbonyl, cyano, nitro (-NO 2 ), aryl, heteroaryl, arylalkyl, alkyl disulfide (e.g., alkyl-S-S-), aryl disulfide (e.g., aryl-S-S-), acetal (alkyl(O-alkyl)2), thioacetal (alkyl(S-alkyl)2), fluorenylmefhoxycarbonyl or
  • the substituents X, A, B and C are chosen independently from one another.
  • X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
  • the aromatic carbocycle is a biphenyl
  • the substituents X, A, B or C may be, independently, on one or both rings. This is similarly so for other aromatic carbocyclic rings or ring systems as defined above.
  • modification of the substituents produces a derivatized aromatic carbocycle.
  • the nature of the substituents X, A, B and C must be compatible with the reaction conditions used for modifying said substituents without said conditions being capable of cleaving the aryl silane bond of the resin- bound aryl silane intermediate.
  • synthetic chemistry conventional in the art may then be performed on the cleaved derivatized aromatic carbocycle to convert the strong electron withdrawing group into a different functionality, e.g., conversion of a nitro group into an amino group using known reaction conditions.
  • synthetic chemistry which are compatible with the goal of derivatizing the resin-bound aromatic carbocycle, without also cleaving the aryl silane bond of the resin-bound aryl silane intermediate, will be obvious to one of ordinary skill in the art.
  • additional synthetic chemistry is used herein at all occurrences to mean one or a series of chemical reactions which are performed on the resin-bound aryl silane intermediate, in particular to modify or derivatize substituents X, A, B and C, prior to cleavage of the aromatic carbocycle from the resin-bound aryl silane intermediate, wherein said chemical reactions are compatible with and non-reactive with the aryl silane bond and may be used to prepare derivatives of the aromatic carbocycle. It will be recognized by the skilled artisan that the additional synthetic chemistry performed on the resin-bound aryl silane intermediate is done so prior to cleavage of the aryl silane bond.
  • Chemical reactions which are compatible with the resin-bound aryl silane intermediate are reactions which effectuate the swelling of the polymeric resin thereby allowing penetration of the reagents to react with the aromatic carbocycle.
  • Chemical reactions which are reactive with the aryl silane bond i.e., they cause cleavage of the aryl silane bond, and therefore are not among the additional synthetic chemistry that may be used in the methods of this invention, are for example, chemical reactions which use strongly acidic conditions or strong electrophilic oxidizing agents (e.g., benzoyl peroxide under acidic conditions).
  • G-protein coupled receptor(s) is used herein at all occurrences to mean a membrane receptor using G-proteins as part of their signaling mechanism, including, but not limited to muscarinic acetylcholine receptors, adenosine receptors, adrenergic receptors, LL-8R receptors, dopamine receptors, endothelin receptors, histamine receptors, calcitonin receptors, angiotensin receptors and the like.
  • assay is used herein at all occurrences to mean a binding assay or a functional assay known or obvious to one of ordinary skill in the art, including, but not limited to, the assays disclosed herein.
  • a particularly suitable assay for use according to the invention is disclosed by Lerner et al., Proc. Natl. Acad. Sci. U.S.A., 91 (5), pp. 1614-1618 (1994).
  • batches or “pools” are used herein at all occurrences to mean a collection of compounds or compound intermediates.
  • alkyl is used herein at all occurrences to mean a straight or branched chain radical of 1 to 20 carbon atoms, unless the chain length is limited thereto, including, but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, sec- butyl, isobutyl, tert-butyl, and the like.
  • the alkyl chain is 1 to 10 carbon atoms in length, more preferably 1 to 8 carbon atoms in length.
  • alkenyl is used herein at all occurrences to mean a straight or branched chain radical of 2-20 carbon atoms, unless the chain length is limited thereto, including, but not limited to, ethenyl, 1-propenyl, 2-propenyl, 2-methyl-l- propenyl, 1-butenyl, 2-butenyl, and the like.
  • the alkenyl chain is 2 to 10 carbon atoms in length, more preferably, 2 to 8 carbon atoms in length.
  • alkynyl is used herein at all occurrences to mean a straight or branched chain radical of 2-20 carbon atoms, unless the chain length is limited thereto, wherein there is at least one triple bond between two of the carbon atoms in the chain, including, but not limited to, acetylene, 1- propylene, 2-propylene, and the like.
  • the alkynyl chain is 2 to 10 carbon atoms in length, more preferably, 2 to 8 carbon atoms in length.
  • alkenyl or alkynyl moiety there is an alkenyl or alkynyl moiety as a substituent group
  • unsaturated linkage i.e., the vinylene or acetylene linkage is preferably not directly attached to a nitrogen, oxygen or sulfur moiety.
  • alkoxy is used herein at all occurrences to mean a straight or branched chain radical of 1 to 20 carbon atoms, unless the chain length is limited thereto, bonded to an oxygen atom, including, but not limited to, methoxy, ethoxy, n- propoxy, isopropoxy, and the like.
  • the alkoxy chain is 1 to 10 carbon atoms in length, more preferably 1 to 8 carbon atoms in length.
  • cycloalkyl and “cyclic alkyl” are used herein at all occurrences to mean cyclic radicals, preferably comprising 3 to 10 carbon atoms which may be mono- or bicyclo- fused ring systems which may additionally include unsaturation, including, but not limited to, cyclopropyl, cyclopentyl, cyclohexyl, 1,2,3,4- tetrahydronaphthyl, and the like.
  • aryl or “heteroaryl” are used herein at all occurrences to mean 5-
  • aromatic ring(s) or ring systems which may include bi- or tri-cyclic systems and one or more heteroatoms, wherein the heteroatoms are selected from oxygen, nitrogen or sulfur.
  • Representative examples include, but are not limited to, phenyl, naphthyl, pyridyl, quinolinyl, thiazinyl, isoquinoline, imidazole, 3,4-dimethoxyphenyl, 3,4-methylenedioxyphenyl, 3,4- dimethoxybenzyl, 3,4-methylenedioxy-benzyl, benzhydryl, 1-naphthylmethyl, 2- naphthylmethyl, fluorenyl, biphenyl-4-methyl, furanyl, and the like.
  • heteroatom is used herein at all occurrences to mean an oxygen atom ("O"), a sulfur atom ("S”) or a nitrogen atom (“N”). It will be recognized that when the heteroatom is nitrogen, it may form an NRiR 2 moiety, wherein R 1 and R 2 are, independently from one another, hydrogen or C j to Cg alkyl, or together with the nitrogen to which they are bound, form a saturated or unsaturated 5-, 6-, or 7- membered ring.
  • arylalkyl and heteroarylalkyl are used herein at all occurrences to mean an aryl or heteroaryl moiety, respectively, that is connected to a Cj.g alkyl moiety as defined above, such as, but not limited to, benzyl.
  • 5- 6-, or 7-membered ring is used herein at all occurrences to mean that substituents R 1 and R 2 , together with the nitrogen to which they are bound, form a saturated or unsaturated ring structure containing at least one additional heteroatom selected from oxygen, nitrogen or sulfur, including, but not limited to morpholine, piperazine, piperidine, pyrolidine, pyridine, and the like.
  • heterocyclic is used herein at all occurrences to mean a saturated or wholly or partially unsaturated 4-10 membered ring system in which one or more rings contain one or more heteroatoms selected from the group consisting of O, N, or S; including, but not limited to, pyrrolidine, piperidine, piperazine, morpholine, imidazolidine, pyrazolidine, benzodiazepines, and the like.
  • halogen is used herein at all occurrences to mean chloro, fluoro, iodo and bromo.
  • Ph is used herein at all occurrences to mean phenyl.
  • substituents may be further substituted by groups similar to those indicated above herein to give substituents such as halo- substituted alkyl (e.g., -CF3), aryl-substituted alkyl, alkoxy-substituted alkyl and the like.
  • substituents such as halo- substituted alkyl (e.g., -CF3), aryl-substituted alkyl, alkoxy-substituted alkyl and the like.
  • Preferred optional substituents for use herein include alkyl, alkenyl, alkoxy, cyano, NO 2 , halogen, preferably bromine, -(CR 1 1 R 12 ) n C(O)R, -(CR 1 1 R 1 ) n -SR' ) -(CR 1 1 R 12 ) n -N(R') and aryl, preferably phenyl. More preferably, the optional substituents are C ⁇ to CJQ alkyl, Ci to C 10 alkoxy, cyano, C(O)R', NO 2 , halogen, and aryl.
  • polypeptide is used herein at all occurrences to mean a polymer of amino acids (i.e., acid units chemically bound together with amide linkages (CONH)), forming a chain that consists of 1 to 20 amino acid residues.
  • non-peptide compounds bind to a variety of receptors, particularly, G-protein coupled receptors.
  • the following core structures may be used as templates for designing libraries of non-peptide compounds which may be tested for binding to a variety of receptors, specifically, G-protein coupled receptors.
  • the libraries can be prepared on a solid support, e.g., a resin, or they can be prepared in solution.
  • the variable substituents can be added by reacting core structure, labeled R, with a mixture of reagents designed to introduce substituents Xl- collectively or by reacting aliquots of R with individual reagents each one of which will introduce a single substituent R; and then mixing the resultant products together (wherein i,j and k are used herein to represent any of the substituents on the compound members of the combinatorial library).
  • the components of the library are screened in groups of multiple compounds. Therefore, once the library of compounds has been synthesized, there must be some method to deconvolute the results of screening such that individual active compounds can be identified. Based upon the disclosure herein, it will be clear to the skilled artisan that there are many methods for decon volution of the combinatorial library. For example, if the compounds of the library are screened on a solid support, they may be physically segregated so that individual active compounds may be directly selected and identified.
  • the library may be deconvoluted in an iterative approach, which involves resynthesis of mixtures of decreasing complexity until a single compound is identified, or in a scanning approach, in which the various substituents on the core structure R, are evaluated independently and the structure of active compounds are determined deductively. Both the iterative and scanning approaches to deconvolution of the combinatorial libraries of this invention are described in more detail below.
  • the iterative approach to deconvoluting the combinatorial library involves separation of the combinatorial library of compounds immediately prior to the introduction of the last variable substituent.
  • R is the core structure, etc., as used above
  • m Yi- is partitioned into p aliquots (wherein m, n and p are integers which define the size of the library, and which range between 1 to 1000; preferably between 1 to 100; most preferably between 1 to 20). Each of those aliquots is reacted with reagents designed to introduce a single substituent, labeled Z.
  • the library is prepared again, this time splitting the mixture of compounds RXi- into n aliquots for introduction of the n different Y substituents (as used herein " “, “b” and “c” refer to specific acceptable substituents which have been determined to be active by screening in a binding or functional assay).
  • the Z ⁇ substituent is introduced into each of the still separated aliquots.
  • the library now consists of n pools RX ⁇ .
  • the appropriate X substituent, labeled X c is determined by beginning with m different aliquots of core structure R and sequentially introducing Xjt, Yfr and Z a to give m different pools RXfcY£Z fl , each of which contains a single compound.
  • Xjt, Yfr and Z a m different pools
  • RXfcY£Z fl m different pools
  • m + n +p syntheses are required to decon volute a library containing m x n xp compounds.
  • the iterative approach is specific for a single target which is determined after the first round of screening, since subsequent library preparations do not contain the full complement of substituents.
  • the application of the scanning approach to deconvoluting the combinatorial library requires that the variable substituents X, Y and Z can be introduced synthetically independently of each other.
  • the library is first prepared as
  • RXl- Yl- w Z exactly as in the iterative approach to give p pools RXi- Y ⁇ _ n Z , each of which contains m x n compounds with all possible variation of X and Y represented but only one particular Z. Screening this library defines the appropriate Z substituents for the desired activity. Since Y can be introduced independently from X and Z, the library is then prepared as RXi- Y Zi- ⁇ , giving n pools of compounds each containing m p compounds in which all substituents X and Z are represented with a particular Y substituent. Screening this library in a binding or functional assay defines the appropriate Y substituents for the desired activity.
  • the library is then prepared as RXjfcYi- n Zi- , giving m batches or pools of compounds, each of which contains n xp compounds in which all substituents Y and Z are represented with a particular X substituent. Screening this library in a binding or functional assay defines the appropriate X substituents for the desired activity.
  • each library contains all the possible permutations of X, Y and Z and can be utilized to screen against a number of different biological targets.
  • the Use of Silicon Chemistry in Preparing Combinatorial Libraries The use of the instant silicon-based resins has been discovered to be particularly effective in preparing, by resin-bound synthesis, core structure(s) which are substituted aromatic carbocycle(s), wherein said aromatic carbocycle(s) comprises an aromatic carbon which carbon has a hydrogen, halogen, hydroxy or acyloxy group bound to it after the resin-bound synthesis is completed.
  • the aromatic carbocycle prepared by resin-bound synthesis utilizing silicon chemistry may be useful as receptor ligands, particularly G-protein coupled receptor ligands, enzyme inhibitors and channel blockers.
  • the instant polymeric resins and silane linkers are particularly useful in effectuating the cleavage of an aromatic carbocycle from a polymeric resin support while leaving a hydrogen at the cleavage position.
  • the silicon linkers, polymeric resin supports and intermediates of this invention effectuate the successful preparation of a single aromatic carbocycle or a plurality of molecularly diverse aromatic carbocycles which, upon cleavage from a polymeric resin support, have a halogen, hydroxy or acyloxy group at the cleavage position.
  • the aromatic carbocycles prepared by the methods described herein can be screened in assays developed for determining lead compounds as pharmaceutical agents.
  • the invention is in a method for preparing a compound by resin-bound synthesis, wherein said compound is an aromatic carbocycle comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said method comprising the steps of: (i) attaching the aromatic carbon to a polymeric resin support through a silane linker to give a resin-bound aryl silane intermediate; and (ii) performing additional synthetic chemistry on the substituent so that the aromatic carbocycle is derivatized.
  • the derivatized resin-bound aryl silane intermediate may be stored for further derivatization of the substituents.
  • the aromatic carbocycle is biphenyl, phenyl, naphthyl or anthracenyl.
  • the aromatic carbocycle has at least one substituent that is X, A, B or C, as defined above, to be derivatized by additional synthetic chemistry.
  • a compound prepared by this method remains as a resin-bound aryl silane intermediate, which resin-bound intermediate may be screened in a suitable assay developed for determining pharmaceutical activity.
  • the derivatized aromatic carbocycle may be decoupled from the resin-bound aryl silane intermediate by a further step comprising cleaving the resin-bound aryl silane intermediate at the aryl silane bond so that the decoupled aromatic carbocycle resulting from the cleavage has a hydrogen, halogen, hydroxy or acyloxy group on the aromatic carbon where it was bound through the silane linker. After this step, the decoupled aromatic carbocycle may be screened in a suitable assay developed for determining pharmaceutical activity.
  • the additional synthetic chemistry performed in order to modify the substituents X, A, B or C must be such that the aromatic carbocycle is derivatized without cleaving the aryl silane bond of the resin-bound aryl silane intermediate.
  • the aromatic carbocycle is bound to a polymeric resin support through a silane linker to give a resin-bound aryl silane intermediate.
  • the aromatic carbocycle is bound to the resin through a silane linker group comprising the following moiety: D-CH 2 -Si-R"R"', wherein D is defined as a C j to C 20 alkyl chain optionally having one or more intervening heteroatoms and/or optionally substituted aryl groups, and R" and R'" are independently, Ci to C ⁇ alkyl.
  • Preferred silane linker groups of formula D-CH2-Si-R"R'" for use in the methods disclosed herein include, but are not limited to, the following linker groups: -(CH2)4-Si-R"R'", wherein D is -(CH 2 )3-; -O-CH 2 -Ph-O-CH 2 -Si-R"R'", wherein D is -O-CH 2 -Ph-O-; -O-Ph-O- CH 2 -SiR"R'", wherein D is -O-Ph-O-; or -O-Ph-CH2-O-CH 2 -Si-R"R'", wherein D is - O-PI1-CH2-O-.
  • a preferred silane linker group for preparing aromatic carbocycles wherein a substituent X, A, B, or C is cyano is a linker group of formula D-CH2 ⁇ Si- R"R'", wherein D is -O-Ph-O-.
  • the aromatic carbon atom of the aromatic carbocycle is bound directly to a silicon atom of the silane linker.
  • R" and R'" are independently, C1 to C4 alkyl, more preferably, R" and R'" are both methyl or ethyl, more preferably R" and R'" are both methyl.
  • Useful intermediates of the invention are the novel aryl silane compounds of Formula (LB).
  • the compounds of Formula (LB) are reacted with an appropriate polymer resin in order to make a resin-bound aryl silane intermediate which will be further modified by performing additional synthetic chemistry thereon.
  • an aryl silane compound is formed as a first intermediate, which intermediate is then coupled to a polymeric resin support.
  • a suitable resin-bound aryl silane intermediate is prepared by combining an aryl silane compound of Formula (LB):
  • R" and R' independently from one another, are Cj to Cg alkyl;
  • X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro, aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester group, provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl; and n is an integer from 1 to 10, with an appropriate polymeric resin, using conventional techniques.
  • a preferred embodiment of this inventive intermediate is a compound of Formula (IB) wherein R" and R'", independently from one another, are Cj to C4 alkyl; X is bromine or iodine; A, B and C are hydrogen; and n is 1 to 4.
  • R" and R"' are each methyl; X is bromine; A, B and C are hydrogen; and n is 1.
  • the compound of Formula (LB) may then be reacted with a suitable polymeric resin support to form a resin-bound aryl silane intermediate.
  • suitable resins for use herein are a cross-linked polystyrene resin, a polyethylene glycol- polystyrene based resin, or a polypropylene glycol based resin.
  • a preferred resin for reaction with a compound of Formula (LB) is a chloromethyl cross-linked divinylbenzene polystyrene resin.
  • Suitable additional synthetic chemistry may be performed on this resin-bound aryl silane intermediate, particularly on the substituents X, A, B or C, as described above, in order to modify the substituents X, A, B or C.
  • the derivatized aromatic carbocycle may be cleaved from the resin-bound aryl silane intermediate at the aryl silane bond or it may remain as a resin-bound aryl silane intermediate.
  • the intermediate compounds of Formula (IB) may be prepared by utilizing another useful intermediate of this invention, i.e., a compound of Formula (LLB):
  • R" and R"' independently from one another, are C j to Cg alkyl;
  • X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro, aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or an orthoester group, provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl; Y is halogen or hydroxyl; and n is an integer from 1 to 10.
  • a preferred embodiment of this aspect of the invention is a compound of Formula (LIB) wherein R" and R'", independently from one another, are Cj to C4 alkyl; X is halogen; A, B and C are hydrogen; Y is bromine; and n is 1 to 4.
  • a more preferred embodiment of this aspect of the invention is a compound of Formula (LLB) wherein R" and R'" are each methyl; X is bromine; A, B and C are hydrogen; Y is bromine; and n is 1.
  • the novel intermediates of Formula (LLB) may easily be prepared from compound 1 -Scheme 1. or appropriate analogs thereof, by reaction with an alkyl lithium compound.
  • a compound of Formula (LLB) may be prepared by forming a Grignard reagent of compound 1 -Scheme 1. or appropriate analogs thereof.
  • An illustrative method for preparing an intermediate of Formula (LLB) is disclosed by Morikawa et al., Polym. J., 24, p. 573 (1992), the relevant parts of which are incorporated herein by reference.
  • substituents X, A, B and C aside from being compatible with the additional synthetic chemistry to be performed on the resin-bound aryl silane intermediate, substituents X, A, B and C must also be compatible with the alkyl lithium chemistry utilized to make the intermediates of Formulae (LB) and ( LB).
  • a number of suitable conditions may be used, for example, treatment of the resin- bound aryl silane intermediate with a strong protic acid.
  • the acidic cleavage conditions include, but are not limited to, treatment with 100% trifluoroacetic acid ("TFA”), hydrofluoric acid (“HF”), hydrochloric acid (“HCl”), pyridinium hydrofluoride, sulfuric acid (“H2SO4"), trifluoromethanesulfonic acid (commonly referred to as triflic acid), boron trifluoride ("BF 3 "), methanesulfonic acid or mixtures thereof.
  • TFA trifluoroacetic acid
  • HF hydrofluoric acid
  • HCl hydrochloric acid
  • pyridinium hydrofluoride pyridinium hydrofluoride
  • sulfuric acid H2SO4
  • trifluoromethanesulfonic acid commonly referred to as triflic acid
  • boron trifluoride boron trifluoride
  • methanesulfonic acid or mixtures thereof Preferred cleavage conditions utilize 100% TFA.
  • base catalyzed cleavage conditions include, but are not limited to, cleavage with NaOH in DMSO (dimethylsulfoxide) or methanol. See, for example, Cretney et al., J. Organometal. Chem., 28, pp. 49-52 (1971).
  • a number of suitable conditions may be used, for example, treatment of the resin- bound aryl silane intermediate with bromine, chlorine or iodine.
  • a number of suitable conditions may be used, for example, treatment of the resin-bound aryl silane intermediate with benzoyl peroxide to give a benzoate ester at the cleavage site.
  • the resulting aromatic carbocycle which is substituted with an ester functionality may be subsequently hydrolyzed using known conditions to yield an aromatic carbocycle which is substituted with a hydroxy group.
  • a number of suitable conditions may be used, for example, treatment of the resin-bound aryl silane intermediate with acetyl peroxide or any suitable acyl peroxide using conventional conditions known to the skilled artisan.
  • this invention is in a method for preparing a library of diverse resin-bound aromatic carbocycles each comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said method comprising the steps of: (i) attaching the aromatic carbon atom of each of a plurality of aromatic carbocycles to an individual polymeric resin support through a silane linker to give a plurality of resin-bound aryl silane intermediates; (ii) optionally dividing said resin-bound aryl silane intermediates into a plurality of portions; (iii) performing additional synthetic chemistry on the substituents so that the aromatic carbocycle is derivatized; and (iv) optionally recombining the portions.
  • the substituents on the aromatic carbocycle which are to be derivatized are X, A, B or C as defined above.
  • the libraries are considered to be combinatorial libraries because the compounds generated from the synthetic methods are molecularly diverse and are prepared simultaneously.
  • the libraries may be prepared on polymeric resin supports using the silane linkers described herein above. For example, a plurality of aromatic carbocycles each comprising an aromatic carbon atom and having at least one substituent X, A, B or C that is not hydrogen or alkyl, are each attached to an individual polymer resin support through a silane linker to give a plurality of resin-bound aryl silane intermediates.
  • the plurality of resin-bound aryl silane intermediates may be reacted with one or more reagents in one reaction vessel.
  • aliquots of the resin- bound aryl silane intermediates may be reacted with one or more reagents and then the resultant products are mixed together to form a library of derivatized aromatic carbocycles.
  • the reagent(s) used in this first step modification will modify only a single substituent X, A, B or C.
  • This first modified/derivatized library may then be further derivatized by repeating the process of dividing and recombining the derivatized resin-bound aryl silane intermediates formed by the additional synthetic chemistry.
  • the resin-bound aryl silane intermediates may be divided into portions at any point during the synthetic scheme. The portions may be recombined at any point during the scheme or, further iterations may be applied if more derivatization is required.
  • the derivatized aliquots may be recombined and reacted with one or more additional reagents in one reaction vessel.
  • each aliquot may be subdivided into further aliquots and reacted as described herein.
  • each polymeric resin support bears a single (derivatized) aromatic carbocycle species created by the additional synthetic chemistry performed on the resin-bound aryl silane intermediate.
  • the desired library is one that comprises an N- methylated compound of formula 8 and an N-ethylated compound of formula 8, the following variation on the split-synthesis method of Moss et al., Ann. Rep. Med. Chem., 28, p. 315 (1993), for preparing libraries of compounds may be used.
  • the steps depicted in Scheme 6 are followed, without dividing the resin-bound aryl silane intermediates of formulae 1 through 5 into portions.
  • said resin-bound formula 6 is divided into a number of portions, for example, two portions, labeled for purposes of illustration as portion 1 and portion 2.
  • Each of the two portions contains resin-bound aryl silane intermediate 6-Scheme 6.
  • Portion 1 is reacted under standard conditions with, e.g., methyl iodide, in order to obtain a compound 7_z Scheme 6. wherein R 4 is methyl.
  • Portion 2 is reacted under standard conditions, with, e.g., ethyl bromide, in order to obtain compound 7-Scheme 6. wherein R 4 is ethyl.
  • the two separate portions are recombined to form a library of two compounds, wherein each polymer resin is linked through a silane linker group, to a distinct aromatic carbocycle which is the product of a specific reaction sequence.
  • the methods and linkers described herein may be applied to the preparation of a large variety of core structures, including aromatic carbocycles.
  • the silicon linker group (which comprises D-CH2-Si-R"R') is suitably bound to an aromatic carbon on the aromatic portion of the core structure, such as in a benzodiazepine derivative or in a tetrahydronaphthyl derivative.
  • the compounds can be separated and characterized by conventional analytical techniques known to the skilled artisan, for example infrared spectrometry or mass spectrometry.
  • the compounds may be characterized while remaining resin-bound or they can be cleaved from the resin- bound aryl silane intermediates using the conditions described above, and then analyzed.
  • some of the compound members of the library may be cleaved from the resin-bound aryl silane intermediates while other members of the library remain resin bound to give a "partially cleaved" library of compounds.
  • a "fully cleaved" library of compounds is created.
  • aromatic carbocycles coupled to the polymerc resins through the silane linkers illustrated below can be optionally substituted at any appropriate site, depending upon the type of derivatization required.
  • the aromatic carbocycle is a biphenyl
  • the substituents X, A, B or C may be, independently, on one or both rings. This is similarly so for other aromatic carbocyclic rings or ring systems, as defined above.
  • DMF dimethylformamide
  • DMSO dimethylsulfoxide
  • LRMS low resolution mass spectrometry
  • DLEA diisopropylethylamine
  • THF tetrahydrofuran
  • n-BuLi n-butyllithium
  • min is minutes
  • mL is milliliters
  • BnBr is benzylbromide
  • 'OAc is acetate.
  • the resin-bound aryl silane intermediate 4-Scheme 1. wherein X is bromine and A, B and C are each hydrogen, is prepared by reacting Merrifield chloromethyl resin (available from Nova Biochem, 1.4 mM/g of Cl) with the resin-bound aryl silane intermediate alcohol 3-Scheme 1. wherein X is bromine and A, B and C are each hydrogen, in an SN2 displacement as described in Scheme 1.
  • 2-Scheme 1 (or the appropriate analogs) is reacted with a base, (such as sodium methoxide or potassium carbonate) in an aprotic solvent (dimethyl formamide, dimethyl acetamide or DMSO if sodium methoxide is the base; acetone or ethyl methyl ketone if potassium carbonate is the base) to displace the halogen on the silane moiety for coupling with optionally substituted hydroxybenzyl alcohol to prepare an aryl silane compound 3 ⁇ Scheme 1 (i.e., a compound of Formula (LB) wherein R" and R'" are methyl; X is bromine; A, B and C are hydrogen; and n is 1).
  • a base such as sodium methoxide or potassium carbonate
  • an aprotic solvent dimethyl formamide, dimethyl acetamide or DMSO if sodium methoxide is the base; acetone or ethyl methyl ketone if potassium carbonate is the base
  • X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyamino- carbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
  • Scheme 2 wherein X is bromine and A, B and C are hydrogen, is depicted starting from the Wang resin 1 -Scheme 2.
  • Scheme 2 depicts the preparation of an aromatic carbocycle (4-Scheme 2. wherein X is bromine) from a resin-bound aryl silane intermediate (2-Scheme 2. wherein X is bromine), wherein the aromatic carbocycle has a hydrogen atom at the site of cleavage from the resin.
  • the Wang resin 1 -Scheme 2 is prepared according to the published procedure of Su-Sun Wang, JACS, 95, p. 1328 (1973) starting from the Merrifield resin. Elemental analysis of 2-Scheme 2. wherein X is bromine and A, B and C are hydrogen, indicated a conversion of approximately 70%.
  • X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyamino-carbonyl, cyano, nitro (- NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is C j to C4 alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
  • Reaction sequence (a) depicts the preparation of an aromatic carbocycle 2c Scheme 3.
  • X is, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t- butoxyaminocarbonyl, cyano, nitro (-NO 2 ), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR) 3 , wherein R is Cj to C4 alkyl), preferably halogen, and most preferably bromine, and wherein A, B and C are hydrogen.
  • 2-Scheme 3. wherein there is a hydrogen atom left on the aromatic carbocycle at the cleavage site, is synthesized through an aryl silane intermediate which is bound to a suitable resin (such as the Merrifield resin or the Wang resin), wherein cleavage of 2-Scheme 3 from the resin is accomplished using strong acidic conditions.
  • a suitable resin such as the Merrifield resin or the Wang resin
  • Preparation of an aromatic carbocycle 3-Scheme 3. wherein there is a halogen atom left on the aromatic carbocycle at the site of cleavage from the silane resin intermediate is accomplished by reacting the resin- bound aryl silane intermediate with an elemental halogen compound (such as Br2, 12 or CI2) in a suitable aprotic solvent (such as methylene chloride).
  • reaction sequences may be applied, wherein X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is C ⁇ to C4 alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
  • n-BuLi, THF, Phthalic anhydride available from Aldrich
  • n-BuLi, THF, CO2 available from Aldrich
  • n-BuLi, THF, Diethyloxalate available from Aldrich
  • Reaction sequence (a) depicts the preparation of 2a-Scheme 4. wherein the para-bromine moiety on resin-bound aryl silane intermediate 1 -Scheme 4 is substituent X which is then modified by additional synthetic chemistry (such as creation of an alkyl lithium species in an aprotic solvent such as THF) to gi e 2a- Scheme 4. wherein X is defined as shown in Scheme 4.
  • Reaction sequence (b) depicts the preparation of 2b-Scheme 4.
  • reaction sequence (c) depicts the preparation of 2c-Scheme 4. wherein the para-bromine moiety on resin-bound aryl silane intermediate 1 -Scheme 4 is substituent X which is then modified by additional synthetic chemistry (such as creation of an alkyl lithium species in an aprotic solvent such as THF) to give 2b-Scheme 4. wherein X is a carboxylic acid moiety.
  • Reaction sequence (c) depicts the preparation of 2c-Scheme 4. wherein the para-bromine moiety on resin-bound aryl silane intermediate 1 -Scheme 4 is substituent X which is then modified by additional synthetic chemistry (such as creation of an alkyl lithium species in an aprotic solvent such as THF) to give Z z Scheme 4. wherein X is a ketoester moiety.
  • the moieties A, B and C may be as defined above.
  • Scheme 5 illustrates additional synthetic chemistry that was successfully performed in order to prepare an aromatic carbocycle (biphenyl) with a hydrogen left at the cleavage site, according to this invention.
  • the resin-bound aryl silane intermediate 1 -Scheme 5 (prepared similarly to 4-Scheme 1). wherein X is bromine, and A, B and C are hydrogen, is reacted with phenylboronic acid and (Pb ⁇ P ⁇ Pd (available from Aldrich) in a mixture of an aprotic and a protic solvent to yield the resin-bound aryl silane intermediate 2c Scheme 5. Subsequent cleavage of resin-bound aryl silane intermediate 2-Scheme 5 under strong acidic conditions produces the aromatic carbocycle biphenyl, 3-Scheme 5. This key reaction is used according to this invention in order to synthesize a variety of biphenyls substituted with various functional groups with conventional chemistry that will be obvious to the skilled artisan.
  • X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, - C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (- NO 2 ), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxy-carbonyl or orthoester (-C(OR) 3 , wherein R is Cj to C alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl, and provided that the chemistry is compatible with modifying the substituent
  • n-BuLi THF, optionally substituted phthalic anhydride
  • (b) (i) (PhO)2P(O)N 3 , Et3N, Toluene; (ii) NaOH, MeOH; (c) (i) peptide coupling; (ii) Deprotection with 20% piperidine in DMF; (d) DMF, 5% acetic acid; (e) 4-benzyl lithium oxazolidinone, THF, R 4 -Z; (f) TFA.
  • the resin-bound aryl silane intermediate 3-Scheme 6 is prepared using the general procedure outlined above for preparing 2a-Scheme 4. using optionally substituted phthalic anhydride, wherein the optional substituent(s) is Y', and Y' is hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (- NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmeth-oxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl).
  • substituent R 3 is hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyamino-carbonyl, cyano, nitro (-NO 2 ), aryl, heteroaryl arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl).
  • Deprotection of 4-Scheme 6 is accomplished with conventional techniques (such as 20% piperidine in DMF) to produce 5-Scheme 6.
  • Cyclization of 5-Scheme 6 is accomplished with an organic acid (such as acetic acid) in an aprotic solvent (such as DMF) to produce 6-Scheme 6.
  • Analogs of 6-Scheme 6 may be N-alkylated at the position- 1 nitrogen of the benzodiazepine ring (depicted in the scheme as R 4 ), using conventional techniques, for example, reaction with a base (such as 4-benzyl lithium oxazolidinone) in an aprotic solvent and alkylation with an alkyl halide or alkyl tosylate (such as R 4 -Z, wherein R 4 is alkyl; and Z is Br, I or tosylate).
  • a base such as 4-benzyl lithium oxazolidinone
  • alkyl halide or alkyl tosylate such as R 4 -Z, wherein R 4 is alkyl; and Z is Br, I or tosylate.
  • Cleavage of the resin-bound aryl silane intermediate 7-Scheme 6 to produce an optionally substituted aromatic carbocycle, i.e., the benzodiazepine &z Scheme 6. is accomplished by treatment with strong acid
  • X is Br and A, B and C are hydrogen.
  • substituents X, A, B and C on the staring material are as defined more broadly, above.
  • 4b-Scheme 6 may be synthesized through a nitrobenzophenone intermediate.
  • Scheme 7 illustrates a method for preparing 1,3- or 1 ,4-diaminobenzene compounds, one of the various types of aromatic carbocycles that may be prepared using the silane linkers of this invention:
  • R" and R'" are methyl; the substituents X and A are bromine and nitro, respectively; B and C are hydrogen; Y is bromine; and n is 1, is prepared by forming a lithium species of 2,4- dibromonitrobenzene (Aldrich) and subsequent reaction with a silane compound (such as bromomethyl chlorodimethyl silane available from Aldrich) in an aprotic solvent (such as THF or ether).
  • aprotic solvent such as THF or ether
  • a strong base such as sodium methoxide or potassium carbonate
  • an optionally substituted benzyl alcohol in an aprotic solvent (such as THF, dimethyl formamide, dimethyl acetamide or DMSO if sodium methoxide is the base; acetone or ethyl methyl ketone if potassium carbonate is the base) to prepare the aryl silane intermediate of 3-Scheme 7.
  • a strong base such as sodium methoxide or potassium carbonate
  • an aprotic solvent such as THF, dimethyl formamide, dimethyl acetamide or DMSO if sodium methoxide is the base; acetone or ethyl methyl ketone if potassium carbonate is the base
  • This intermediate is coupled with a polymer resin (such as Merrifield resin, Wang resin, or any other suitable resin described herein) in an aprotic solvent (such as THF) using a base (such as sodium hydride, sodium methoxide in THF, dimethyl formamide, dimethyl acetamide or DMSO, or potassium carbonate in acetone or ethyl methyl ketone) to produce 4-Scheme 7.
  • a base such as sodium hydride, sodium methoxide in THF, dimethyl formamide, dimethyl acetamide or DMSO, or potassium carbonate in acetone or ethyl methyl ketone
  • substituents B, C, R 5 and R 6 are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (-NO 2 ), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR) 3 , wherein R is Cj to C 4 alkyl).
  • Scheme 8 illustrates a method for preparing amino carboxy compounds, another class of aromatic carbocycles that may be prepared using the silane linkers of this invention:
  • substituents B, C, R 7 and R 8 are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)R a , wherein R a is hydrogen or alkyl, cyano, t-butoxyaminocarbonyl, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR) 3 , wherein R is Cj to C4 alkyl), is accomplished under strongly acidic conditions (such as treatment with TFA).
  • Scheme 9 illustrates a method for preparing biphenyltetrazole compounds, yet another class of aromatic carbocycles that may be prepared using the silane linkers of this invention.
  • 2-Scheme 9 (wherein X and A are bromine and B and C are defined as described above) prepared by reacting 1 -Scheme 9 (prepared from 2,4- dibromobenzoic acid which is available from Aldrich, by reaction with methanesulfonyl chloride and ammonia) with sodium azide in the presence of a Lewis acid, and then N-alkylating the intermediate previously formed, using conventional techniques, for example, reaction with a base (such as NaH, potassium carbonate or trialkylamines) in an aprotic solvent, and alkylation with an alkyl halide or an alkyl tosylate (such as R 9 -Z', wherein R 9 is alkyl; and Z' is Cl, Br, I or tosylate).
  • a base such as NaH, potassium carbonate or trialkylamines
  • alkylation with an alkyl halide or an alkyl tosylate such as R 9 -Z', wherein R 9 is alkyl; and
  • 2-Scheme 9 is coupled with a silane compound and then with a polymer resin to prepare 4-Scheme 9. as described previously. Additional synthetic chemistry is performed in order to modify the aromatic carbocycle bound to the resin. Cleavage of the substituted aromatic carbocycle is accomplished using strong acid conditions. It will be clear that X and A can be other than bromide and as defined above, provided that X, A, B and C can not all be hydrogen and not all X, A, B and C can be alkyl.
  • Scheme 10 illustrates the preparation of an aromatic carbocycle 3-Scheme
  • Scheme 11 illustrates the preparation of an amine substituted biphenyl compound using the resin-bound aryl silane intermediate 1 -Scheme 11 (prepared according to step (a) of Scheme 10 above) as a starting material.
  • 1 -Scheme 11 is reacted with an optionally substituted primary amine (such as benzyl amine, Aldrich ®, Milwauke, WI ) in an aprotic or protic solvent (such as toluene, methylene chloride, ethanol or methanol) to give a resin-bound aryl silane intermediate substituted with a benzyl imine (2-Scheme 11).
  • an optionally substituted primary amine such as benzyl amine, Aldrich ®, Milwauke, WI
  • an aprotic or protic solvent such as toluene, methylene chloride, ethanol or methanol
  • the optionally substituted primary amine is substituted with alkyl, aryl heteroaryl, arylalkyl or heteroarylalkyl; preferably arylalkyl; more preferably, benzyl.
  • Additional synthetic chemistry specifically a Grignard reaction using allylmagnesium bromide (made conventionally) in an aprotic solvent (such as ether and toluene), is performed on resin-bound aryl silane intermediate 2-Scheme 11 to convert the benzyl imine to 3 ⁇ Scheme 11. an aminobenzyl substituted alkenyl moiety.
  • Compounds analogous to 3-Scheme 11. but wherein the alkenyl moiety is varied, may be prepared prepared by using a different Grignard reagent under the same reaction conditions. Standard cleavage conditions are used to give 4-Scheme 11.
  • Scheme 12 illustrates the preparation of another substituted biphenyl compound using the resin-bound aryl silane intermediate 1 -Scheme 12 (prepared according to step (a) of Scheme 10 above) as a starting material.
  • an aprotic solvent such
  • the vinyl ester 2c scheme 12 is modified to a thiol addition moiety by reaction with an optionally substituted thiol (such as thiophenol, Aldrich) in a tertiary amine base (such as triethylamine) in an aprotic or protic solvent (such as toluene or ethanol) to give resin-bound aryl silane intermeidate 3-Scheme 12. which intermediate is cleaved to give the desired derivatized aromatic carbocycle, 4-Scheme 12. It will be recognized that various additional synthetic chemistry can be performed on intermediate 2c Scheme 12 in order to derivatize across the alkenyl bond, for example by performing a Wadsworth-Emmons reaction as disclosed by Patios, Tet.
  • an optionally substituted thiol such as thiophenol, Aldrich
  • a tertiary amine base such as triethylamine
  • aprotic or protic solvent such as toluene or ethanol
  • Phj P CHCOOEt, THF, 60°; b) PhSH, EN, Toluene, 25° ; c) TFA, Neat
  • Schemes 13a and 13b illustrate other types of additional synthetic chemistry which are compatible with the aryl silane bond of various resin-bound aryl silane intermediates.
  • Scheme 14 merely illustrates the standard reaction conditions for making dibromobenzonitrile (starting material 1 -Scheme 15).
  • Scheme 15 illustrates the reaction conditions for making a cyano, bromo- substituted aryl silane compound 4-Scheme 15.
  • Scheme 16 illustrates the preparation of a resin 2-Scheme 16. starting from the Merrifield chloromethyl resin 1 -Scheme 16.
  • Scheme 17 illustrates the preparation of a cyano-substituted aromatic carbocycle using the cyano, bromo-substituted aryl silane compound 2-Scheme 17 (prepared per Scheme 15) and resin 1 -Scheme 17 (prepared per Scheme 16) as starting materials.
  • Ph3P is triphenylphosphine (Aldrich);
  • DEAD is diethylazodicarboxylate (Aldrich);
  • NMM is N-methyl mo ⁇ holine (Aldrich).
  • the instant invention includes a silane linker of formula D-CH 2 -Si-R"R" ⁇ wherein D is -(CH2)3-, i.e., -(CH2)4-Si-R"R' M , as an appropriate silane linker to carry out solid phase synthesis of increasing complexity, particularly when the possibility of undesired side products upon cleavage of the final product from the resin-bound aryl silane intermediate, exists.
  • Scheme 18 illustrates the preparation of a resin-bound aryl silane intermediate 3-Scheme 18. utilizing an all carbon silane linker of formula D-CH -Si- R"R'", wherein D is -(CH 2 )3-, i.e., -(CH 2 )4-Si-R"R'", wherein R" and R'" are each methyl.
  • Scheme 18(a) illustrates the preparation of 2-Scheme 18(a) which is a reagent used in the preparation of 3-Scheme 18. described above.
  • Scheme 19 illustrates the preparation of a sulfonamide aromatic carbocycle ., 1 -Scheme 19) as the starting material.
  • Scheme 20 illustrates the use of an acid labile MOM protecting group with the all carbon silane linker.
  • the usefullness of this reaction scheme is the demonstartion that 10% TFA is useful in deprotecting 2-Scheme 20. however, 10% TFA does not cleave the aromatic carbocycle from the resin-bound aryl silane intermediate 3-Scheme 20.
  • Resin-bound aryl silane intermediate 4-Scheme 1 (0.5 g) was swelled in methylene chloride(5 mL). Bromine(0.1 mL) was added and stirred overnight. Reaction mixture, after filtering, washing with ether and removal of solvents in vacuo, gave an oil (175 mg) which solidified on standing. It was found to be dibromobenzene by l NMR and m. pt.
  • Resin-bound aryl silane intermediate 4-Scheme 1 (500 mg) was suspended in methylene chloride (5 mL). Gaseous HBr was then passed through the suspension cooled in an ice bath for 5 minutes. The cooling bath was removed and the reaction mixture stirred for 30 minutes. Excess HBr was purged from the suspension by passing Argon until no HBr was detected with pH paper. The resin was filtered off, washed with ether and the solvents removed in vacuo to give 230 mg of an oil. MPLC (silica, ethyl acetate: hexane 1:10) provided the product. MS (DCI, NH3) 428 (M+ +NH4). Reaction resin-bound aryl silane intermediate 4-Scheme 1 with trifluoroacetic acid (See Scheme 3(a))
  • Resin-bound aryl silane intermediate 4-Scheme 1 (500 mg) was stirred in trifluoroacetic acid (2 mL) and the product was analyzed by GC(SE-30, 50°C) room temperature 5.14 minutes. The formation of bromobenzene was confirmed by co- injection with authentic bromobenzene. Preparation of resin-bound aryl silane intermediate 2a-Scheme 4
  • the resin-bound aryl silane intermediate 2a-Scheme 4 was suspended in toluene and allowed to swell for 30 minutes. To this was added diphenylphosphoryl azide and the mixture is heated in an oil bath maintained at 90°C for 16 h. The reaction mixture was cooled and filtered, washed with methanol, methylene chloride, methanol and finally dried in vacuo to give the isocyanate. IR 2100 cm -1 .
  • the resin-bound aryl silane intermediate 5-Scheme 19 was treated with TFA:DMS:H2 ⁇ (90:5:5) for 16 h.
  • the solvents were removed under vacuo to provide a pale yellow oil which was compared with an authentic sample prepared earlier.
  • silicon linkers and silicon based polymer resins of this invention may be used in a variety of combinatorial methods for synthesizing a large number of molecularly diverse compounds, simultaneously.
  • the instant invention may be applied to (i) the "multi-pin" method described in Geysen et al., Proc. Natl. Acad. Sci. USA., 81, p. 3998 (1984); U.S. Patent 4,708,871 (1987); Geysen et al., Bioorg. Med. Chem. Lett, 3, p.397 (1993); and European Patent 138,855 (1991); (ii) the "tea-bag” approach described in Houghten, R.A., Proc. Natl. Acad. Sci. USA., 82, p. 5131 (1985); and Houghten et al., Nature, 354, p. 84 (1991); and (iii) chemical synthesis on a "chip” described in Fodor et al., Science, 251, p. 767 (1991) and U.S. Patent 5,143,854 (1992).
  • the compounds may be screened in assays which have been developed for determining lead compounds as pharmaceutical agents.
  • the components of the library are screened in groups of multiple compounds. Therefore, once the library of compounds has been synthesized, there must be some method to deconvolute the results of screening such that individual active compounds can be identified. Based upon the disclosure herein, it will be clear to the skilled artisan that there are many methods for deconvolution of the combinatorial library. For example, if the compounds of the library are screened on a solid support, they may be physically segregated so that individual active compounds may be directly selected and identified.
  • the library may be deconvoluted in an iterative approach, which involves resynthesis of mixtures of decreasing complexity until a single compound is identified, or in a scanning approach, in which the various substituents on the aromatic carbocycle, are evaluated independently and the structure of active compounds are determined deductively.
  • iterative and scanning approaches to deconvolution of a combinatorial library of compounds see, for example, Houghten et al., Nature, 354, p. 84 (1991).
  • a representative binding assay is as follows. Other binding assays or functional assays that are known by, or that would be obvious to the skilled artisan, may be performed as well. Tissue containing the appropriate target receptor are homogenized, filtered through cheesecloth and centrifuged at 1500 x g for 10 minutes. The supernatant is decanted and the pellet is resuspended in an appropriate incubation buffer, e.g. 75 mM Tris.HCl, pH 7.4 containing 12.5 mM MgCl and 1.5 mM EDTA. Membranes equivalent to 100 g protein are incubated with 50 pmol radiolabeled receptor ligand and an appropriate amount of the test library mixture in a total volume of 5001 for 1 hr.
  • an appropriate incubation buffer e.g. 75 mM Tris.HCl, pH 7.4 containing 12.5 mM MgCl and 1.5 mM EDTA.
  • the binding reaction is terminated by dilution with the addition of 5 mL of cold incubation buffer and the bound tracer is separated from free by filtration on Whatman GF/C filter paper. The filter paper is washed several times with cold incubation buffer and then counted to determine the amount of bound ligand.
  • Specific binding is defined as the portion of radiolabeled receptor ligand binding which can be completed by a high concentration of unlabeled receptor ligand.
  • the presence of a competing ligand in the library test mixture is evidenced by a reduction in specific binding of the radiolabeled receptor ligand in the presence of the library test mixture.

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Abstract

This invention also relates to novel silicon-based polymer resins and silane linkers, methods for their preparation and their use in the synthesis of libraries of compounds to be screened as pharmaceutical agents.

Description

COMPOUNDS AND METHODS
FIELD OF THE INVENTION
This application (Serial No. 08/738,379, filed October 25, 1996) is a continuation-in-part application of Serial No. 08/663,148, filed June 12, 1996, which is a continuation-in-part application of International Application PCT US94/14414, filed December 15, 1994, which claims priority from Serial No. 08/235,624, filed April 29, 1994, and GB 9325621.2, filed December 15, 1993. This invention relates to libraries of non-peptide compounds each comprised of a core structure and methods for making such libraries. This invention also relates to novel silicon-based polymer resins and silane linkers, methods for their preparation and their use in the synthesis of libraries of aromatic carbocycles to be screened as pharmaceutical agents.
BACKGROUND OF THE INVENTION
In the continuing search for new chemical moieties that can effectively modulate a variety of biological processes, the standard method for conducting a search is to screen a variety of pre-existing chemical moieties, for example, naturally occurring compounds or compounds which exist in synthetic libraries or databanks. The biological activity of the pre-existing chemical moieties is determined by applying the moieties to an assay which has been designed to test a particular property of the chemical moiety being screened, for example, a receptor binding assay which tests the ability of the moiety to bind to a particular receptor site. In an effort to reduce the time and expense involved in screening a large number of randomly chosen compounds for biological activity, several developments have been made to provide libraries of compounds for the discovery of lead compounds. The chemical generation of molecular diversity has become a major tool in the search for novel lead structures. Currently, the known methods for chemically generating large numbers of molecularly diverse compounds generally involve the use of solid phase synthesis, in particular to synthesize and identify peptides and peptide libraries. See, for example, Lebl et al., Int. J. Pept. Prot. Res., 41, p. 201 (1993) which discloses methodologies providing selectively cleavable linkers between peptide and resin such that a certain amount of peptide can be liberated from the resin and assayed in soluble form while some of the peptide still remains attached to the resin, where it can be sequenced; Lam et al., Nature, 354, p. 82 (1991) and (WO 92/00091) which disclose a method of synthesis of linear peptides on a solid support such as polystyrene or polyacrylamide resin; Geysen et al., J. Immunol. Meth., 102, p. 259 (1987) which discloses the synthesis of peptides on derivatized polystyrene pins which are arranged on a block in such a way that they correspond to the arrangement of wells in a 96-well microtiter plate; and Houghten et al., Nature, 354, p. 84 (1991) and WO 92/09300 which disclose an approach to de novo determination of antibody or receptor binding sequences involving soluble peptide pools.
The major drawback, aside from technical considerations, with all of these methods for lead generation is the quality of the lead. Linear peptides historically have represented relatively poor leads for pharmaceutical design. In particular, there is no rational strategy for conversion of a linear peptide into a non-peptide lead. As noted above, one must resort to screening large databanks of compounds, with each compound being tested individually, in order to determine non-peptide leads for peptide receptors.
It is known that a wide variety of organic reactions can be carried out on substrates immobilized on resins. These include, in addition to peptide synthesis reactions which are well known to those of ordinary skill in the art, nucleophilic displacements on benzylic halides, halogenation, nitration, sulfonation, oxidation, hydrolysis, acid chloride formation, Friedel-Crafts reactions, reduction with LiAlH4, metallation, and reaction of the organometallic polymer with a wide variety of reagents. See, for example, N. K. Mathur et al., Polymers as Aids in Organic
Chemistry, Academic Press, New York, p. 18 (1980). In addition, Farrall et al., J. Org. Chem., 41, p. 3877 (1976) describe the experimental details of some of these reactions carried out with resins.
The above-mentioned known organic reactions when applied to solid phase synthesis using known polymeric resins, yield non-peptide compounds containing auxiliary functional groups such as carboxyl, phenolic hydroxyl, amine, amide or bulky groups, all of which have their own unique pharmacological properties. A hydrogen atom offers its own unique pharmacological properties. However, currently, there exists no solid phase synthetic resin linker directly bonded to a carbon atom of a compound, which, upon cleavage of the compound from the resin, yields a compound with a hydrogen on the carbon at the cleavage position. See, for example, Bunin, B.A. & Ellman J.A., JACS, 114, pp. 10997-10998 (1992), which reports the solid-phase synthesis of 1,4-benzodiazepine derivatives. Unlike the instant invention, that method is limited by requisite introduction of auxiliary functionality, e.g., carboxylic acid, in the target molecule in order to facilitate attachment to the solid support. Furthermore, no apparatus or method for multiple, simultaneous synthesis is described by Bunin & Ellman. It has now been discovered, as disclosed herein, that silicon-based polymer resins are useful in the preparation of a single compound, e.g., an aromatic carbocycle, or a library of molecularly diverse compounds which are aromatic carbocycles, each comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said aromatic carbons having a hydrogen, halogen, hydroxy or acyloxy group bound to them after cleavage from the resin.
It has also been discovered that certain non-peptide compounds, each comprised of a core structure, bind to a variety of receptors, in particular, G-protein coupled receptors. It has further been discovered that the core structures, including aromatic carbocycles, may be used as templates for developing libraries of non- peptide compounds which are analogs of the core structures. Therefore, rather than synthesizing individual analogs of these non-peptide compounds for screening, large numbers of non-peptide compounds which may be receptor ligands, in particular G- protein coupled receptor ligands, can be synthesized by the combinatorial methods described herein and screened in assays developed for determining lead compounds as pharmaceutical agents. The methods disclosed herein may also be applied to obtain libraries of compounds, including aromatci carbocycles, that are enzyme inhibitors, receptor ligands or channel blockers.
The current methods for generation of lead compounds have a variety of limitations, therefore, demonstrating the necessity for new methods for generating and determining lead compounds as pharmaceutical agents.
SUMMARY OF THE INVENTION
The present invention is directed to non-peptide compounds, each comprised of a core structure. The present invention is also directed to the use of these core structures as templates for developing libraries of non-peptide compounds which are analogs of the core structures. Further, this invention is directed to libraries of compounds which comprise receptor ligands, in particular, G-protein coupled receptor ligands, enzyme inhibitors and channel blockers and the combinatorial synthetic methods for making such libraries of compounds. Still further this invention relates to novel silicon-based polymer resins, methods for preparing said resins and intermediates used in the preparation of said resins. In this regard, one aspect of this invention relates to methods for preparing one or a plurality of derivatized compounds by resin-bound synthesis, wherein the compounds are aromatic carbocycles each comprising an aromatic carbon atom and at least one substituent X, A, B or C that is not hydrogen or alkyl, said aromatic carbons having a hydrogen, halogen, hydroxy or acyloxy group bound to them after cleavage from the resin. In particular, this aspect of the invention relates to methods for utilizing silicon chemistry to effectuate the cleavage of an aromatic carbocycle from a polymer resin while leaving a hydrogen, halogen, hydroxy or acyloxy group on the aromatic carbocycle at the cleavage position. Yet further, the present invention is directed to methods for screening a compound or plurality of compounds made according to the synthetic methods disclosed herein, which comprise using the compounds in suitable assays developed for detecting the compounds' utility as pharmaceutical agents. In addition, this invention relates to a method of screening G-protein coupled receptors with ligands that are known to bind other G-protein coupled receptors, or that are related to ligands that are known to bind other G- protein coupled receptors.
DETAILED DESCRIPTION OF THE INVENTION
The term "core structure(s)" is used herein at all occurrences to mean a core molecular structure(s) which is derived from compounds which have been shown to interact with a receptor, in particular, a G-protein coupled receptor, and which is used as a template for designing the libraries of compounds to be made. Core structures may be aromatic carbocycles as defined below.
The term "library of compounds" is used herein at all occurrences to mean a series or plurality of compounds derivatized from their core structure. Suitably, the core structure used for designing a library of compounds is an aromatic carbocycle. The term "combinatorial library" is used herein at all occurrences to mean a collection of compounds based upon a core structure, for example, an aromatic carbocycle structure, wherein the library contains a discrete number of independently variable substituents, functional groups or structural elements, and further, wherein the library is designed so that, for the range of chemical moieties selected for each of the independently variable substituents, compounds containing all possible permutations of those substituents will be present in the library. Thus, by way of illustration, if a core structure, labeled R, contains three independently variable substituents, labeled X, Y and Z, and if X is taken from m different chemical moieties, Y from n different chemical moieties and Z from p different chemical moieties (wherein m, n and p are integers which define the size of the library, and which range between 1 to 1000; preferably between 1 to 100; most preferably between 1 to 20), then the library would contain m x n xp different chemical compounds and all possible combinations of X, Y and Z would be present on the core structure R within that library. The methods for preparing combinatorial libraries of compounds are such that the molecularly diverse compound members of the libraries are synthesized simultaneously.
The term "aromatic carbocycle" is used herein at all occurrences to mean a compound which comprises a single ring or a fused ring system, preferably 5-14 membered ring systems, and, for purposes herein, includes an optionally substituted biphenyl, composed of carbon atoms having aromatic character, e.g., characterized by delocalized electron resonance and the ability to sustain a ring current and which ring or ring systems may include one or more heteroatoms selected from oxygen, nitrogen or sulfur. The aromatic carbocycle may be optionally substituted by one or more substituents herein described as "substituent X", "substituent A", "substituent B" or "substituent C". When the aromatic carbocycle is a biphenyl, the substituents X, A, B or C may be, independently, on one or both rings. This is similarly so for other aromatic carbocyclic rings or ring systems as defined above. It will be recognized by the skilled artisan that a large number of aromatic carbocycles may be made using the silane linkers of this invention, provided that the chemistry used to prepare the aromatic carbocycles is compatible with the aryl silane bond, defined below. Suitable aromatic carbocycles include, but are not limited to, optionally substituted phenyl rings, optionally substituted naphthyl rings, optionally substituted tetrahydronaphthyl rings, optionally substituted anthracenyl rings, optionally substituted 1-, 2- or 3- tetrahydrobenzazepines; optionally substituted 1,4-, 1,5-, or 2,4- tetrahydrobenzodiazepines; optionally substituted biphenyl tetrazoles; optionally substituted 1,3- or 1,4-diaminobenzene compounds; or optionally substituted 1,3- or 1,4-aminocarboxyphenyl compounds. Suitably, the aromatic carbocycles described herein may serve as core structures, and therefore, as templates for designing libraries of compounds to be screened as pharmaceutical agents. Suitably, the aromatic carbocycles are G-protein coupled receptor ligands, channel blockers and/or enzyme inhibitors.
The terms "resin-bound synthesis" and "solid phase synthesis" are used herein interchangeably to mean one or a series of chemical reactions used to prepare either a single compound or a library of molecularly diverse compounds, wherein the chemical reactions are performed on a compound, suitably, an aromatic carbocycle, which is bound to a polymeric resin support through an appropriate linkage, suitably, an silane linker.
The terms "resin," "inert resin," polymeric resin" or "polymeric resin support" are used herein at all occurrences to mean a bead or other solid support such as beads, pellets, disks, capillaries, hollow fibers, needles, solid fibers, cellulose beads, pore-glass beads, silica gels, grafted co-poly beads, poly-acrylamide beads, latex beads, dimethylacrylamide beads optionally cross-linked with N,N'-bis- acryloyl ethylene diamine, glass particles coated with a hydrophobic polymer, etc., i.e., a material having a rigid or semi-rigid surface. The solid support is suitably made of, for example, cross linked polystyrene resin, polyethylene glycol- polystyrene resin, benzyl ester resins or benzhydrylamine resins and any other substance which may be used as such and which would be known or obvious to one of ordinary skill in the art. For purposes herein, it will be obvious to the skilled artisan, that when the linker to the resin is silicon-based, the above terms mean any aliphatic or aromatic polymer which lacks functionality known to participate in the additional synthetic chemistry for generation of the derivatized compounds of this invention, and which is stable to conditions for protodesilylation. Preferred polymer resins for use herein are the Merrifield resin (available commercially from Nova Biochem) and the Wang resin (synthesis described below). The compounds (or libraries of compounds) made by the instant methods may either remain bound to the resin which is used to perform the resin-bound synthesis (hereinafter referred to as "resin-bound compounds (or libraries)") or not bound to a resin (hereinafter referred to as "soluble compounds (or libraries)").
The terms "silane linker" or "silane linker group" are used herein at all occurrences to mean the moiety which binds the aromatic carbocycle to the polymeric resin support, which linker comprises a silicon atom bound to an alkyl chain comprising one or more methylene groups, said alkyl chain optionally having one or more intervening heteroatoms and/or aryl groups, or combinations thereof. Suitable silane linkers for use in this invention comprise a moiety of the following formula: -D-CH2-Si-R"R'", wherein R" and R'" are independently, Ci to C alkyl, and D is a Cj to C20 alkyl chain optionally having one or more intervening heteroatoms and/or optionally substituted aryl groups. It will be recognized that the alkyl chain may contain both intervening heteroatoms and intervening optionally substituted aryl groups. Preferably, R" and R" are independently, C to C4 alkyl, more preferably, R" and R"' are both methyl or ethyl, more preferably methyl. The term "aryl silane compound" is used herein at all occurrences to mean an intermediate compound comprising an aromatic carbocycle having an aromatic carbon and at least one substituent X, A, B or C that is not hydrogen or alkyl, wherein the aromatic carbon is bound to a silane linker through an aryl silane bond. Suitably, an aryl silane compound within the scope of this invention is defined by a compound of Formula (LB).
The term "aryl silane bond" is used herein at all occurrences to mean the bond between the aromatic carbon of an aromatic carbocycle and the silicon atom of a silane linker. Suitably, after the resin-bound synthesis is performed, this bond is cleaved in order to decouple the aromatic carbocycle from the resin-bound aryl silane intermediate.
The term "resin-bound aryl silane intermediate" is used herein at all occurrences to mean an intermediate wherein an aromatic carbocycle is directly bound to a silane linker, which linker is directly bound to a polymeric resin support. Therefore, it will be recognized that a resin-bound aryl silane intermediate is a moiety which couples an aromatic carbocycle to a polymeric resin support through a silane linker. The terms "substituent X," "substituent A," "substituent B," and "substituent
C" are used herein at all occurrences to mean a non-nucleophilic substituent, including, but not limited to, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether (e.g., -alkyl-S -alkyl-), alkylthio (e.g., alkyl-SH), C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyamino-carbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide (e.g., alkyl-S-S-), aryl disulfide (e.g., aryl-S-S-), acetal (alkyl(O-alkyl)2), thioacetal (alkyl(S-alkyl)2), fluorenylmefhoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl). The substituents X, A, B and C are chosen independently from one another. In addition, X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl. When the aromatic carbocycle is a biphenyl, the substituents X, A, B or C may be, independently, on one or both rings. This is similarly so for other aromatic carbocyclic rings or ring systems as defined above. As used herein, modification of the substituents produces a derivatized aromatic carbocycle. The nature of the substituents X, A, B and C, must be compatible with the reaction conditions used for modifying said substituents without said conditions being capable of cleaving the aryl silane bond of the resin- bound aryl silane intermediate. Therefore, it will be recognized that when modification of substituents X, A, B or C by performing additional synthetic chemistry thereon, utilizes reaction conditions such that the aryl silane bond is subject to cleavage, it is desirable to choose a strong electron withdrawing group as the substituent(s). Additional synthetic chemistry can then be performed to modify the substituent(s) without cleavage of the aryl silane bond. Subsequent to performing the additional synthetic chemistry to modify the substituent(s), it is possible to cleave the aryl silane bond which decouples the aromatic carbocycle from the resin-bound aryl silane intermediate. If desired, synthetic chemistry conventional in the art may then be performed on the cleaved derivatized aromatic carbocycle to convert the strong electron withdrawing group into a different functionality, e.g., conversion of a nitro group into an amino group using known reaction conditions. Given this disclosure, the types of synthetic chemistry which are compatible with the goal of derivatizing the resin-bound aromatic carbocycle, without also cleaving the aryl silane bond of the resin-bound aryl silane intermediate, will be obvious to one of ordinary skill in the art. The term "additional synthetic chemistry" is used herein at all occurrences to mean one or a series of chemical reactions which are performed on the resin-bound aryl silane intermediate, in particular to modify or derivatize substituents X, A, B and C, prior to cleavage of the aromatic carbocycle from the resin-bound aryl silane intermediate, wherein said chemical reactions are compatible with and non-reactive with the aryl silane bond and may be used to prepare derivatives of the aromatic carbocycle. It will be recognized by the skilled artisan that the additional synthetic chemistry performed on the resin-bound aryl silane intermediate is done so prior to cleavage of the aryl silane bond. Chemical reactions which are compatible with the resin-bound aryl silane intermediate, are reactions which effectuate the swelling of the polymeric resin thereby allowing penetration of the reagents to react with the aromatic carbocycle. Chemical reactions which are reactive with the aryl silane bond, i.e., they cause cleavage of the aryl silane bond, and therefore are not among the additional synthetic chemistry that may be used in the methods of this invention, are for example, chemical reactions which use strongly acidic conditions or strong electrophilic oxidizing agents (e.g., benzoyl peroxide under acidic conditions).
The term "G-protein coupled receptor(s)" is used herein at all occurrences to mean a membrane receptor using G-proteins as part of their signaling mechanism, including, but not limited to muscarinic acetylcholine receptors, adenosine receptors, adrenergic receptors, LL-8R receptors, dopamine receptors, endothelin receptors, histamine receptors, calcitonin receptors, angiotensin receptors and the like.
The term "assay" is used herein at all occurrences to mean a binding assay or a functional assay known or obvious to one of ordinary skill in the art, including, but not limited to, the assays disclosed herein. A particularly suitable assay for use according to the invention is disclosed by Lerner et al., Proc. Natl. Acad. Sci. U.S.A., 91 (5), pp. 1614-1618 (1994).
The terms "batches" or "pools" are used herein at all occurrences to mean a collection of compounds or compound intermediates.
The term "alkyl" is used herein at all occurrences to mean a straight or branched chain radical of 1 to 20 carbon atoms, unless the chain length is limited thereto, including, but not limited to methyl, ethyl, n-propyl, isopropyl, n-butyl, sec- butyl, isobutyl, tert-butyl, and the like. Preferably the alkyl chain is 1 to 10 carbon atoms in length, more preferably 1 to 8 carbon atoms in length. The term "alkenyl" is used herein at all occurrences to mean a straight or branched chain radical of 2-20 carbon atoms, unless the chain length is limited thereto, including, but not limited to, ethenyl, 1-propenyl, 2-propenyl, 2-methyl-l- propenyl, 1-butenyl, 2-butenyl, and the like. Preferably, the alkenyl chain is 2 to 10 carbon atoms in length, more preferably, 2 to 8 carbon atoms in length.
The term "alkynyl" is used herein at all occurrences to mean a straight or branched chain radical of 2-20 carbon atoms, unless the chain length is limited thereto, wherein there is at least one triple bond between two of the carbon atoms in the chain, including, but not limited to, acetylene, 1- propylene, 2-propylene, and the like. Preferably, the alkynyl chain is 2 to 10 carbon atoms in length, more preferably, 2 to 8 carbon atoms in length.
In all instances herein where there is an alkenyl or alkynyl moiety as a substituent group, the unsaturated linkage, i.e., the vinylene or acetylene linkage is preferably not directly attached to a nitrogen, oxygen or sulfur moiety. The term "alkoxy" is used herein at all occurrences to mean a straight or branched chain radical of 1 to 20 carbon atoms, unless the chain length is limited thereto, bonded to an oxygen atom, including, but not limited to, methoxy, ethoxy, n- propoxy, isopropoxy, and the like. Preferably the alkoxy chain is 1 to 10 carbon atoms in length, more preferably 1 to 8 carbon atoms in length. The terms "cycloalkyl" and "cyclic alkyl" are used herein at all occurrences to mean cyclic radicals, preferably comprising 3 to 10 carbon atoms which may be mono- or bicyclo- fused ring systems which may additionally include unsaturation, including, but not limited to, cyclopropyl, cyclopentyl, cyclohexyl, 1,2,3,4- tetrahydronaphthyl, and the like. The terms "aryl" or "heteroaryl" are used herein at all occurrences to mean 5-
14 membered optionally substituted aromatic ring(s) or ring systems which may include bi- or tri-cyclic systems and one or more heteroatoms, wherein the heteroatoms are selected from oxygen, nitrogen or sulfur. Representative examples include, but are not limited to, phenyl, naphthyl, pyridyl, quinolinyl, thiazinyl, isoquinoline, imidazole, 3,4-dimethoxyphenyl, 3,4-methylenedioxyphenyl, 3,4- dimethoxybenzyl, 3,4-methylenedioxy-benzyl, benzhydryl, 1-naphthylmethyl, 2- naphthylmethyl, fluorenyl, biphenyl-4-methyl, furanyl, and the like.
The term "heteroatom" is used herein at all occurrences to mean an oxygen atom ("O"), a sulfur atom ("S") or a nitrogen atom ("N"). It will be recognized that when the heteroatom is nitrogen, it may form an NRiR2 moiety, wherein R1 and R2 are, independently from one another, hydrogen or Cj to Cg alkyl, or together with the nitrogen to which they are bound, form a saturated or unsaturated 5-, 6-, or 7- membered ring.
The terms "arylalkyl" and "heteroarylalkyl" are used herein at all occurrences to mean an aryl or heteroaryl moiety, respectively, that is connected to a Cj.g alkyl moiety as defined above, such as, but not limited to, benzyl.
The term "5- 6-, or 7-membered ring" is used herein at all occurrences to mean that substituents R1 and R2, together with the nitrogen to which they are bound, form a saturated or unsaturated ring structure containing at least one additional heteroatom selected from oxygen, nitrogen or sulfur, including, but not limited to morpholine, piperazine, piperidine, pyrolidine, pyridine, and the like.
The term "heterocyclic" is used herein at all occurrences to mean a saturated or wholly or partially unsaturated 4-10 membered ring system in which one or more rings contain one or more heteroatoms selected from the group consisting of O, N, or S; including, but not limited to, pyrrolidine, piperidine, piperazine, morpholine, imidazolidine, pyrazolidine, benzodiazepines, and the like.
The term "halogen" is used herein at all occurrences to mean chloro, fluoro, iodo and bromo.
The term "Ph" is used herein at all occurrences to mean phenyl.
The term "optionally substituted" is used herein at all occurrences to mean that the optionally substituted moieties may or may not be substituted with one to three various functional groups including, alkyl, alkenyl, alkynyl, aryl, cycloalkyl, heteroaryl, heterocyclo groups arylalkyl, heteroarylalkyl, halogen, cyano, - (CR1 1R12)n-C(O)R'; -(CR1 1R12)n-NO2;
Figure imgf000012_0001
- (CR1
Figure imgf000012_0002
"(CR1 !R12)n-NHC(O)R'; -(CR1 1R12)n-CO2R';-(CR1 lRl2)n- CON(R')2; -(CR11R12)a(C=C)b(CR1 l 2)cT or
(CR1
Figure imgf000012_0003
lRl2)cZ'; wherein Z' is C(O)R', CO2R', NO2; OR'; SR'; N(R')2 , NHC(O)R'; or CON(R')2; a is 0 or 1, b is 0 to 10 and c is 0 to 10, preferably a=b=c is less than 10; is N or S; R' is hydrogen, (Cj - C4) alkyl, aryl, arylalkyl, or heteroaryl; and R1 ^a d R12 are independently hydrogen or a branched or straight chain C1 to Cg alkyl, alkenyl or alkynyl; and, for purposes herein, n is 0 or is an integer from 1 to 10. It is recognized that these substituents may be further substituted by groups similar to those indicated above herein to give substituents such as halo- substituted alkyl (e.g., -CF3), aryl-substituted alkyl, alkoxy-substituted alkyl and the like. For example, in the term (CR1
Figure imgf000012_0004
n is 1, R11 is -CH2CH=CH2, R12 is hydogen, one of R' is hydrogen and one of R'is benzyl; in the term -(CR1 R12)nSR', n is 1, R' is phenyl, R12 is hydrogen, R1 1 is a substituted alkyl, specifically a methyl substituted by -COOR' and R' is hydrogen, methyl or ethyl; in the term alkenyl, the alkenyl moiety may be substituted by -(CR1 1R12)n-C(O)R or -(CR1 1R12)n-CO2R', wherein R is hydrogen, methyl or ethyl; in the term (CR1 1R12)a(C=C)b(CR1 lRl2)c Z', a is 1, b is 1, c is 0, Z' is NR', R11 and R12 are H and R is benzyl; in the term
Figure imgf000013_0001
W is N and a is 1, b is 1, c is 0, Z' is NR', R11 and R12 are H and R' is benzyl.
Preferred optional substituents for use herein include alkyl, alkenyl, alkoxy, cyano, NO2, halogen, preferably bromine, -(CR1 1R12)nC(O)R, -(CR1 1R1 )n-SR') -(CR1 1R12)n-N(R') and aryl, preferably phenyl. More preferably, the optional substituents are C\ to CJQ alkyl, Ci to C10 alkoxy, cyano, C(O)R', NO2, halogen, and aryl.
The term "polypeptide" is used herein at all occurrences to mean a polymer of amino acids (i.e., acid units chemically bound together with amide linkages (CONH)), forming a chain that consists of 1 to 20 amino acid residues.
Certain non-peptide compounds bind to a variety of receptors, particularly, G-protein coupled receptors. Suitably, the following core structures may be used as templates for designing libraries of non-peptide compounds which may be tested for binding to a variety of receptors, specifically, G-protein coupled receptors.
Benzodiazepines of formula (I):
Figure imgf000013_0002
Formula (I)
N-phenylimidazoles of formula (II):
Figure imgf000013_0003
Formula (LI)
Oxindoles of formula (UI):
Figure imgf000014_0001
Formula (III)
Indole carboxylic amines or acids of formula (IV):
Figure imgf000014_0002
Aminobenzazepines of formula (V):
Figure imgf000014_0003
Surprisingly, it has been discovered that compounds which comprise any one of these core structures, when tested in assays developed for determining lead compounds as pharmaceutical agents, demonstrate activity more often than would be expected by the skilled artisan. These core structures may be used as templates for developing synthetic libraries by the combinatorial methods described herein. The libraries of compounds can then be screened in assays developed for determining lead compounds as pharmaceutical agents. If the core structures are used as templates for making the libraries of compounds, the number of individual compounds which are likely to be active in a particular assay will be higher than the skilled artisan would expect when using standard methods of synthesizing individual compounds randomly for screening as pharmaceutical agents. Also, by making and screening the libraries of compounds based upon core structures, the probability of identifying a chemical lead for use as a pharmaceutical agent is enhanced.
Combinatorial Synthesis Methods: Based upon the disclosure herein, it will be clear to one of ordinary skill in the art that there are many possible synthetic approaches to creating the libraries of this invention. The libraries can be prepared on a solid support, e.g., a resin, or they can be prepared in solution. For example, the variable substituents can be added by reacting core structure, labeled R, with a mixture of reagents designed to introduce substituents Xl- collectively or by reacting aliquots of R with individual reagents each one of which will introduce a single substituent R; and then mixing the resultant products together (wherein i,j and k are used herein to represent any of the substituents on the compound members of the combinatorial library).
For reasons of efficiency, the components of the library are screened in groups of multiple compounds. Therefore, once the library of compounds has been synthesized, there must be some method to deconvolute the results of screening such that individual active compounds can be identified. Based upon the disclosure herein, it will be clear to the skilled artisan that there are many methods for decon volution of the combinatorial library. For example, if the compounds of the library are screened on a solid support, they may be physically segregated so that individual active compounds may be directly selected and identified. In contrast, if the compounds of the library are tested as soluble mixtures, the library may be deconvoluted in an iterative approach, which involves resynthesis of mixtures of decreasing complexity until a single compound is identified, or in a scanning approach, in which the various substituents on the core structure R, are evaluated independently and the structure of active compounds are determined deductively. Both the iterative and scanning approaches to deconvolution of the combinatorial libraries of this invention are described in more detail below.
Iterative approach
In its simplest form, the iterative approach to deconvoluting the combinatorial library involves separation of the combinatorial library of compounds immediately prior to the introduction of the last variable substituent. Using the same nomenclature, i.e., R is the core structure, etc., as used above, the mixture of compounds RXι .mYi- is partitioned into p aliquots (wherein m, n and p are integers which define the size of the library, and which range between 1 to 1000; preferably between 1 to 100; most preferably between 1 to 20). Each of those aliquots is reacted with reagents designed to introduce a single substituent, labeled Z. Thus, p different pools RXι_ Yι_ Z , each of which contains m x n compounds with all possible variations of X and Y being represented but only one particular Z, will be obtained. Screening this library in a binding or functional assay defines the appropriate Z substituent(s) for the desired activity.
Once the appropriate Z substituent, labeled Za, is determined (for illustrative purposes, only one active compound exists, however, it would be clear to the skilled artisan that more than one active compound may exist in the library), the library is prepared again, this time splitting the mixture of compounds RXi- into n aliquots for introduction of the n different Y substituents (as used herein " ", "b" and "c" refer to specific acceptable substituents which have been determined to be active by screening in a binding or functional assay). After the Y substituents are introduced, the Zα substituent is introduced into each of the still separated aliquots. The library now consists of n pools RX\.mYjZa, each of which contains m different compounds with all the possible X substituents represented, and one particular Y substituent. Screening this library in a binding or functional assay defines the appropriate Y substituent, labeled Y&.
In a similar manner, the appropriate X substituent, labeled Xc is determined by beginning with m different aliquots of core structure R and sequentially introducing Xjt, Yfr and Za to give m different pools RXfcY£Zfl, each of which contains a single compound. Thus only m + n +p syntheses are required to decon volute a library containing m x n xp compounds.
The iterative approach is specific for a single target which is determined after the first round of screening, since subsequent library preparations do not contain the full complement of substituents.
Scanning approach
The application of the scanning approach to deconvoluting the combinatorial library requires that the variable substituents X, Y and Z can be introduced synthetically independently of each other. The library is first prepared as
RXl- Yl-wZ exactly as in the iterative approach to give p pools RXi- Yι_nZ , each of which contains m x n compounds with all possible variation of X and Y represented but only one particular Z. Screening this library defines the appropriate Z substituents for the desired activity. Since Y can be introduced independently from X and Z, the library is then prepared as RXi- Y Zi-^, giving n pools of compounds each containing m p compounds in which all substituents X and Z are represented with a particular Y substituent. Screening this library in a binding or functional assay defines the appropriate Y substituents for the desired activity.
Since X can also be introduced independently from Y and Z, the library is then prepared as RXjfcYi-nZi- , giving m batches or pools of compounds, each of which contains n xp compounds in which all substituents Y and Z are represented with a particular X substituent. Screening this library in a binding or functional assay defines the appropriate X substituents for the desired activity.
In the simplest case, a single X, Y and Z substituent are identified from the three libraries, thus converging on a single compound RXcY^Zα. The advantage of utilizing the scanning approach is that each library contains all the possible permutations of X, Y and Z and can be utilized to screen against a number of different biological targets.
The Use of Silicon Chemistry in Preparing Combinatorial Libraries The use of the instant silicon-based resins has been discovered to be particularly effective in preparing, by resin-bound synthesis, core structure(s) which are substituted aromatic carbocycle(s), wherein said aromatic carbocycle(s) comprises an aromatic carbon which carbon has a hydrogen, halogen, hydroxy or acyloxy group bound to it after the resin-bound synthesis is completed. The aromatic carbocycle prepared by resin-bound synthesis utilizing silicon chemistry may be useful as receptor ligands, particularly G-protein coupled receptor ligands, enzyme inhibitors and channel blockers.
In contrast to the resins and linkers known in the art, the instant polymeric resins and silane linkers are particularly useful in effectuating the cleavage of an aromatic carbocycle from a polymeric resin support while leaving a hydrogen at the cleavage position. In addition, the silicon linkers, polymeric resin supports and intermediates of this invention effectuate the successful preparation of a single aromatic carbocycle or a plurality of molecularly diverse aromatic carbocycles which, upon cleavage from a polymeric resin support, have a halogen, hydroxy or acyloxy group at the cleavage position. The aromatic carbocycles prepared by the methods described herein can be screened in assays developed for determining lead compounds as pharmaceutical agents.
In one aspect, the invention is in a method for preparing a compound by resin-bound synthesis, wherein said compound is an aromatic carbocycle comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said method comprising the steps of: (i) attaching the aromatic carbon to a polymeric resin support through a silane linker to give a resin-bound aryl silane intermediate; and (ii) performing additional synthetic chemistry on the substituent so that the aromatic carbocycle is derivatized. The derivatized resin-bound aryl silane intermediate may be stored for further derivatization of the substituents. Suitably, the aromatic carbocycle is biphenyl, phenyl, naphthyl or anthracenyl. Suitably, the aromatic carbocycle has at least one substituent that is X, A, B or C, as defined above, to be derivatized by additional synthetic chemistry. A compound prepared by this method remains as a resin-bound aryl silane intermediate, which resin-bound intermediate may be screened in a suitable assay developed for determining pharmaceutical activity. The derivatized aromatic carbocycle may be decoupled from the resin-bound aryl silane intermediate by a further step comprising cleaving the resin-bound aryl silane intermediate at the aryl silane bond so that the decoupled aromatic carbocycle resulting from the cleavage has a hydrogen, halogen, hydroxy or acyloxy group on the aromatic carbon where it was bound through the silane linker. After this step, the decoupled aromatic carbocycle may be screened in a suitable assay developed for determining pharmaceutical activity.
As described above, the additional synthetic chemistry performed in order to modify the substituents X, A, B or C must be such that the aromatic carbocycle is derivatized without cleaving the aryl silane bond of the resin-bound aryl silane intermediate.
According to this invention, the aromatic carbocycle is bound to a polymeric resin support through a silane linker to give a resin-bound aryl silane intermediate. In particular, the aromatic carbocycle is bound to the resin through a silane linker group comprising the following moiety: D-CH2-Si-R"R"', wherein D is defined as a Cj to C20 alkyl chain optionally having one or more intervening heteroatoms and/or optionally substituted aryl groups, and R" and R'" are independently, Ci to Cβ alkyl. Preferred silane linker groups of formula D-CH2-Si-R"R'" for use in the methods disclosed herein include, but are not limited to, the following linker groups: -(CH2)4-Si-R"R'", wherein D is -(CH2)3-; -O-CH2-Ph-O-CH2-Si-R"R'", wherein D is -O-CH2-Ph-O-; -O-Ph-O- CH2-SiR"R'", wherein D is -O-Ph-O-; or -O-Ph-CH2-O-CH2-Si-R"R'", wherein D is - O-PI1-CH2-O-. A preferred silane linker group for preparing aromatic carbocycles wherein a substituent X, A, B, or C is cyano, is a linker group of formula D-CH2~Si- R"R'", wherein D is -O-Ph-O-. For purposes herein, the aromatic carbon atom of the aromatic carbocycle is bound directly to a silicon atom of the silane linker. Preferably, R" and R'" are independently, C1 to C4 alkyl, more preferably, R" and R'" are both methyl or ethyl, more preferably R" and R'" are both methyl. Useful intermediates of the invention are the novel aryl silane compounds of Formula (LB). The compounds of Formula (LB) are reacted with an appropriate polymer resin in order to make a resin-bound aryl silane intermediate which will be further modified by performing additional synthetic chemistry thereon. Preferably, an aryl silane compound is formed as a first intermediate, which intermediate is then coupled to a polymeric resin support. A suitable resin-bound aryl silane intermediate is prepared by combining an aryl silane compound of Formula (LB):
Figure imgf000019_0001
Formula (LB)
wherein R" and R'", independently from one another, are Cj to Cg alkyl; X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro, aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester group, provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl; and n is an integer from 1 to 10, with an appropriate polymeric resin, using conventional techniques.
A preferred embodiment of this inventive intermediate is a compound of Formula (IB) wherein R" and R'", independently from one another, are Cj to C4 alkyl; X is bromine or iodine; A, B and C are hydrogen; and n is 1 to 4. A more preferred embodiment of this invention is wherein R" and R"' are each methyl; X is bromine; A, B and C are hydrogen; and n is 1.
The compound of Formula (LB) may then be reacted with a suitable polymeric resin support to form a resin-bound aryl silane intermediate. Suitable resins for use herein are a cross-linked polystyrene resin, a polyethylene glycol- polystyrene based resin, or a polypropylene glycol based resin. A preferred resin for reaction with a compound of Formula (LB) is a chloromethyl cross-linked divinylbenzene polystyrene resin. Suitable additional synthetic chemistry may be performed on this resin-bound aryl silane intermediate, particularly on the substituents X, A, B or C, as described above, in order to modify the substituents X, A, B or C. In all cases, after the aromatic carbocycle portion of the resin-bound aryl silane intermediate is modified by the additional synthetic chemistry, the derivatized aromatic carbocycle may be cleaved from the resin-bound aryl silane intermediate at the aryl silane bond or it may remain as a resin-bound aryl silane intermediate.
The intermediate compounds of Formula (IB) may be prepared by utilizing another useful intermediate of this invention, i.e., a compound of Formula (LLB):
Figure imgf000020_0001
Formula (LLB)
wherein R" and R"', independently from one another, are Cj to Cg alkyl; X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro, aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or an orthoester group, provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl; Y is halogen or hydroxyl; and n is an integer from 1 to 10. A preferred embodiment of this aspect of the invention is a compound of Formula (LIB) wherein R" and R'", independently from one another, are Cj to C4 alkyl; X is halogen; A, B and C are hydrogen; Y is bromine; and n is 1 to 4. A more preferred embodiment of this aspect of the invention is a compound of Formula (LLB) wherein R" and R'" are each methyl; X is bromine; A, B and C are hydrogen; Y is bromine; and n is 1. As would be obvious to one of ordinary skill in the art, the novel intermediates of Formula (LLB) may easily be prepared from compound 1 -Scheme 1. or appropriate analogs thereof, by reaction with an alkyl lithium compound. In the alternative, a compound of Formula (LLB) may be prepared by forming a Grignard reagent of compound 1 -Scheme 1. or appropriate analogs thereof. An illustrative method for preparing an intermediate of Formula (LLB) is disclosed by Morikawa et al., Polym. J., 24, p. 573 (1992), the relevant parts of which are incorporated herein by reference. In addition, as would be appreciated by the skilled artisan, aside from being compatible with the additional synthetic chemistry to be performed on the resin-bound aryl silane intermediate, substituents X, A, B and C must also be compatible with the alkyl lithium chemistry utilized to make the intermediates of Formulae (LB) and ( LB). In order to cleave the aryl silane bond of the resin-bound aryl silane intermediate, so that a hydrogen is bound to the aromatic carbon at the cleavage site, a number of suitable conditions may be used, for example, treatment of the resin- bound aryl silane intermediate with a strong protic acid. In particular, the acidic cleavage conditions, include, but are not limited to, treatment with 100% trifluoroacetic acid ("TFA"), hydrofluoric acid ("HF"), hydrochloric acid ("HCl"), pyridinium hydrofluoride, sulfuric acid ("H2SO4"), trifluoromethanesulfonic acid (commonly referred to as triflic acid), boron trifluoride ("BF3"), methanesulfonic acid or mixtures thereof. Preferred cleavage conditions utilize 100% TFA. Alternatively, cleavage of the aryl silane bond may be accomplished using base catalyzed cleavage. In particular, base catalyzed cleavage conditions include, but are not limited to, cleavage with NaOH in DMSO (dimethylsulfoxide) or methanol. See, for example, Cretney et al., J. Organometal. Chem., 28, pp. 49-52 (1971). In order to cleave the aryl silane bond of the resin-bound aryl silane intermediate so that a halogen is bound to the aromatic carbon at the cleavage site, a number of suitable conditions may be used, for example, treatment of the resin- bound aryl silane intermediate with bromine, chlorine or iodine.
In order to cleave the aryl silane bond so that a hydroxy group is bound to the aromatic carbon at the cleavage site, a number of suitable conditions may be used, for example, treatment of the resin-bound aryl silane intermediate with benzoyl peroxide to give a benzoate ester at the cleavage site. The resulting aromatic carbocycle which is substituted with an ester functionality may be subsequently hydrolyzed using known conditions to yield an aromatic carbocycle which is substituted with a hydroxy group. In order to cleave the aryl silane bond so that an acyloxy group is bound to the aromatic carbon at the cleavage site, a number of suitable conditions may be used, for example, treatment of the resin-bound aryl silane intermediate with acetyl peroxide or any suitable acyl peroxide using conventional conditions known to the skilled artisan. In yet another aspect, this invention is in a method for preparing a library of diverse resin-bound aromatic carbocycles each comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said method comprising the steps of: (i) attaching the aromatic carbon atom of each of a plurality of aromatic carbocycles to an individual polymeric resin support through a silane linker to give a plurality of resin-bound aryl silane intermediates; (ii) optionally dividing said resin-bound aryl silane intermediates into a plurality of portions; (iii) performing additional synthetic chemistry on the substituents so that the aromatic carbocycle is derivatized; and (iv) optionally recombining the portions. Suitably, the substituents on the aromatic carbocycle which are to be derivatized are X, A, B or C as defined above.
Based upon the disclosure herein, it will be clear to one of ordinary skill in the art that there are many possible synthetic approaches to preparing the libraries of this invention. The libraries are considered to be combinatorial libraries because the compounds generated from the synthetic methods are molecularly diverse and are prepared simultaneously. The libraries may be prepared on polymeric resin supports using the silane linkers described herein above. For example, a plurality of aromatic carbocycles each comprising an aromatic carbon atom and having at least one substituent X, A, B or C that is not hydrogen or alkyl, are each attached to an individual polymer resin support through a silane linker to give a plurality of resin-bound aryl silane intermediates. In a first step modification to the substituent(s) on the aromatic carbocycle, the plurality of resin-bound aryl silane intermediates may be reacted with one or more reagents in one reaction vessel. Alternatively in a first step modification, aliquots of the resin- bound aryl silane intermediates may be reacted with one or more reagents and then the resultant products are mixed together to form a library of derivatized aromatic carbocycles. Preferably, the reagent(s) used in this first step modification will modify only a single substituent X, A, B or C.
This first modified/derivatized library may then be further derivatized by repeating the process of dividing and recombining the derivatized resin-bound aryl silane intermediates formed by the additional synthetic chemistry. It will be obvious to the skilled artisan that the resin-bound aryl silane intermediates may be divided into portions at any point during the synthetic scheme. The portions may be recombined at any point during the scheme or, further iterations may be applied if more derivatization is required. For example, after a first step modification where the aliquots were divided and reacted with one or more appropriate reagents, the derivatized aliquots may be recombined and reacted with one or more additional reagents in one reaction vessel. Alternatively, each aliquot may be subdivided into further aliquots and reacted as described herein.
Therefore, it will be obvious to the skilled artisan that the steps of dividing the portions, performing additional synthetic chemistry and recombining the portions, may each be carried out more than once. The steps of optionally dividing and recombining the resin-bound aryl silane intermediates into portions are for purposes of varying the derivatization, depending upon the type of diversity required for the library of end-product aromatic carbocycles being prepared by the combinatorial synthesis. Suitably, when the libraries of the invention are prepared according to the instant disclosure, each polymeric resin support bears a single (derivatized) aromatic carbocycle species created by the additional synthetic chemistry performed on the resin-bound aryl silane intermediate. For example, in Scheme 6, if the desired library is one that comprises an N- methylated compound of formula 8 and an N-ethylated compound of formula 8, the following variation on the split-synthesis method of Moss et al., Ann. Rep. Med. Chem., 28, p. 315 (1993), for preparing libraries of compounds may be used. The steps depicted in Scheme 6 are followed, without dividing the resin-bound aryl silane intermediates of formulae 1 through 5 into portions. However, prior to N- alkylation of the resin-bound aryl silane intermediate of formula 6, said resin-bound formula 6 is divided into a number of portions, for example, two portions, labeled for purposes of illustration as portion 1 and portion 2. Each of the two portions contains resin-bound aryl silane intermediate 6-Scheme 6. Portion 1 is reacted under standard conditions with, e.g., methyl iodide, in order to obtain a compound 7_z Scheme 6. wherein R4 is methyl. Portion 2 is reacted under standard conditions, with, e.g., ethyl bromide, in order to obtain compound 7-Scheme 6. wherein R4 is ethyl. The two separate portions are recombined to form a library of two compounds, wherein each polymer resin is linked through a silane linker group, to a distinct aromatic carbocycle which is the product of a specific reaction sequence. The methods and linkers described herein may be applied to the preparation of a large variety of core structures, including aromatic carbocycles. However, when utilizing the silicon-based linkers and resin-bound aryl silane intermediates disclosed herein, the silicon linker group (which comprises D-CH2-Si-R"R'") is suitably bound to an aromatic carbon on the aromatic portion of the core structure, such as in a benzodiazepine derivative or in a tetrahydronaphthyl derivative.
According to this invention, after the additional synthetic chemistry has been performed on the resin-bound aryl silane intermediate so that a library of molecularly diverse compounds has been prepared, the compounds can be separated and characterized by conventional analytical techniques known to the skilled artisan, for example infrared spectrometry or mass spectrometry. The compounds may be characterized while remaining resin-bound or they can be cleaved from the resin- bound aryl silane intermediates using the conditions described above, and then analyzed. In addition, some of the compound members of the library may be cleaved from the resin-bound aryl silane intermediates while other members of the library remain resin bound to give a "partially cleaved" library of compounds. Alternatively if all of the members of the library of compounds are cleaved from the resin-bound aryl silane intermediates, a "fully cleaved" library of compounds is created.
General Methods of Preparation
For all of the following Schemes, standard work-up and purification methods can be used and will be obvious to the skilled artisan. In addition, it will be recognized that the aromatic carbocycles coupled to the polymerc resins through the silane linkers illustrated below, can be optionally substituted at any appropriate site, depending upon the type of derivatization required. In particular, when the aromatic carbocycle is a biphenyl, the substituents X, A, B or C may be, independently, on one or both rings. This is similarly so for other aromatic carbocyclic rings or ring systems, as defined above.
As used herein, the following terms have the following meanings: "DMF" is dimethylformamide; "DMSO" is dimethylsulfoxide; "LRMS" is low resolution mass spectrometry; "DLEA" is diisopropylethylamine; "THF" is tetrahydrofuran; "n-BuLi" is n-butyllithium; "min" is minutes; "h" or "hr" is hours; "mL" is milliliters; "RT" or "rt" is room temperature; "BnBr" is benzylbromide; and'OAc" is acetate.
Scheme 1
The resin-bound aryl silane intermediate 4-Scheme 1. wherein X is bromine and A, B and C are each hydrogen, is prepared by reacting Merrifield chloromethyl resin (available from Nova Biochem, 1.4 mM/g of Cl) with the resin-bound aryl silane intermediate alcohol 3-Scheme 1. wherein X is bromine and A, B and C are each hydrogen, in an SN2 displacement as described in Scheme 1.
Figure imgf000025_0001
Figure imgf000025_0002
(a) n-BuLi, THF, -78°C, BrCH2Si(Me)2Cl [bromomethyl chlorodimethyl silane, available from Aldrich]; (b) NaOMe, DMF, p-hydroxybenzyl alcohol; (c) NaH, THF, 70°C, Merrifield resin.
Compounds analogous to intermediate compound 2-Scheme 1 (i.e., a compound of Formula (LLB) wherein R" and R'" are methyl; X is bromine; A, B and C are hydrogen; Y is bromine; and n is 1) may be prepared from an optionally substituted aromatic carbocycle such as 1 -Scheme 1 having a substituent(s) which can be converted by conventional techniques, such as formation of an alkyl (Cj-Cg) lithium species, into a haloalkyl dialkylsilyl substituent. 2-Scheme 1 (or the appropriate analogs) is reacted with a base, (such as sodium methoxide or potassium carbonate) in an aprotic solvent (dimethyl formamide, dimethyl acetamide or DMSO if sodium methoxide is the base; acetone or ethyl methyl ketone if potassium carbonate is the base) to displace the halogen on the silane moiety for coupling with optionally substituted hydroxybenzyl alcohol to prepare an aryl silane compound 3^ Scheme 1 (i.e., a compound of Formula (LB) wherein R" and R'" are methyl; X is bromine; A, B and C are hydrogen; and n is 1). An SN2 displacement of 3-Scheme 1 with a polymer resin is accomplished using strong basic conditions (such as NaH) in an aprotic solvent (such as THF, DMSO, DMF or dimethyl acetamide) providing 4-Scheme 1. As will be clear to the skilled artisan, this reaction sequence can be performed on compound 1 -Scheme 1. wherein X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyamino- carbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
Scheme 2 The synthesis of an isomeric resin-bound aryl silane intermediate of 2ι
Scheme 2. wherein X is bromine and A, B and C are hydrogen, is depicted starting from the Wang resin 1 -Scheme 2. In addition, Scheme 2 depicts the preparation of an aromatic carbocycle (4-Scheme 2. wherein X is bromine) from a resin-bound aryl silane intermediate (2-Scheme 2. wherein X is bromine), wherein the aromatic carbocycle has a hydrogen atom at the site of cleavage from the resin.
Figure imgf000026_0001
Figure imgf000026_0002
(a) 2-Scheme 1. NaH, THF, n-Bu4NI-, 70°C, 4 days; (b) TFA, Neat
The Wang resin 1 -Scheme 2 is prepared according to the published procedure of Su-Sun Wang, JACS, 95, p. 1328 (1973) starting from the Merrifield resin. Elemental analysis of 2-Scheme 2. wherein X is bromine and A, B and C are hydrogen, indicated a conversion of approximately 70%. Preparation of a substituted aromatic carbocycle wherein a hydrogen is left at the site of cleavage from the resin is accomplished according to Scheme 2 by treating the resin-bound aryl silane intermediate 2-Scheme 2 with strong acidic conditions (such as TFA, HCl, H2SO , trifluoromethanesulfonic acid BF3, methanesulfonic acid or mixtures thereof) to give a substituted aromatic carbocycle 4-Scheme 2. Again, as will be clear to one of ordinary skill in the art, this reaction sequence can be performed on compound 2-Scheme 2. wherein X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyamino-carbonyl, cyano, nitro (- NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
Scheme 3 and Scheme 4
The various chemical reactions outlined in Scheme 3 and Scheme 4 show the use of the silicon based polymer resins of this invention for the synthesis of a variety of substituted aromatic carbocycles. As will be obvious, conventional chemistry known to the skilled artisan may be applied to the resin-bound aryl silane intermediates disclosed herein in order to modify the substituents on the starting aromatic carbocycle.
Figure imgf000027_0001
(a) TFA, Neat; (b) Br2, CH2C12. Reaction sequence (a) depicts the preparation of an aromatic carbocycle 2c Scheme 3. wherein X is, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t- butoxyaminocarbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl), preferably halogen, and most preferably bromine, and wherein A, B and C are hydrogen. 2-Scheme 3. wherein there is a hydrogen atom left on the aromatic carbocycle at the cleavage site, is synthesized through an aryl silane intermediate which is bound to a suitable resin (such as the Merrifield resin or the Wang resin), wherein cleavage of 2-Scheme 3 from the resin is accomplished using strong acidic conditions. Preparation of an aromatic carbocycle 3-Scheme 3. wherein there is a halogen atom left on the aromatic carbocycle at the site of cleavage from the silane resin intermediate is accomplished by reacting the resin- bound aryl silane intermediate with an elemental halogen compound (such as Br2, 12 or CI2) in a suitable aprotic solvent (such as methylene chloride). It will be obvious to one of ordinary skill in the art that these reaction sequences may be applied, wherein X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is C\ to C4 alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl.
Scheme 4
Figure imgf000029_0001
X (2b) = CQ, H X (2c) = COC02 Et
(a) n-BuLi, THF, Phthalic anhydride (available from Aldrich); (b) n-BuLi, THF, CO2; (c) n-BuLi, THF, Diethyloxalate (available from Aldrich).
Reaction sequence (a) depicts the preparation of 2a-Scheme 4. wherein the para-bromine moiety on resin-bound aryl silane intermediate 1 -Scheme 4 is substituent X which is then modified by additional synthetic chemistry (such as creation of an alkyl lithium species in an aprotic solvent such as THF) to gi e 2a- Scheme 4. wherein X is defined as shown in Scheme 4. Reaction sequence (b) depicts the preparation of 2b-Scheme 4. wherein the para-bromine moiety on resin- bound aryl silane intermediate 1 -Scheme 4 is substituent X which is then modified by additional synthetic chemistry (such as creation of an alkyl lithium species in an aprotic solvent such as THF) to give 2b-Scheme 4. wherein X is a carboxylic acid moiety. Reaction sequence (c) depicts the preparation of 2c-Scheme 4. wherein the para-bromine moiety on resin-bound aryl silane intermediate 1 -Scheme 4 is substituent X which is then modified by additional synthetic chemistry (such as creation of an alkyl lithium species in an aprotic solvent such as THF) to give Z z Scheme 4. wherein X is a ketoester moiety. The moieties A, B and C may be as defined above.
Scheme 5
Scheme 5 illustrates additional synthetic chemistry that was successfully performed in order to prepare an aromatic carbocycle (biphenyl) with a hydrogen left at the cleavage site, according to this invention.
Figure imgf000030_0001
(a) Phenylboronic acid, (Ph3P)4Pd, Toluene, Ethanol, aq Na2CO3; (b) TFA, Neat.
The resin-bound aryl silane intermediate 1 -Scheme 5 (prepared similarly to 4-Scheme 1). wherein X is bromine, and A, B and C are hydrogen, is reacted with phenylboronic acid and (Pb^P^Pd (available from Aldrich) in a mixture of an aprotic and a protic solvent to yield the resin-bound aryl silane intermediate 2c Scheme 5. Subsequent cleavage of resin-bound aryl silane intermediate 2-Scheme 5 under strong acidic conditions produces the aromatic carbocycle biphenyl, 3-Scheme 5. This key reaction is used according to this invention in order to synthesize a variety of biphenyls substituted with various functional groups with conventional chemistry that will be obvious to the skilled artisan. See, for example, Scheme 10 below which illustrates the use of a substituted boronic acid in order to make a substituted biphenyl (3-Scheme 10V A review of boronic chemistry which is compatible with the aryl silane bond, can be found in Suzuki, Ace. Chem. Res., 15, pp. 178-184 (1982). It will be obvious to one of ordinary skill in the art that additional synthetic chemistry may be similarly performed on resin-bound aryl silane intermediates wherein X, A, B and C are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, - C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (- NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxy-carbonyl or orthoester (-C(OR)3, wherein R is Cj to C alkyl), provided that X, A, B and C can not all be hydrogen and X, A, B and C can not all be alkyl, and provided that the chemistry is compatible with modifying the substituents without cleaving the aryl silane bond.
Scheme 6
Figure imgf000032_0001
Figure imgf000032_0002
Figure imgf000032_0003
4a: Y"=NCO 4b : Y"=NH 2
Figure imgf000032_0004
Scheme 6 (continued)
Figure imgf000033_0001
Figure imgf000033_0002
Figure imgf000033_0003
(a) n-BuLi, THF, optionally substituted phthalic anhydride; (b) (i) (PhO)2P(O)N3, Et3N, Toluene; (ii) NaOH, MeOH; (c) (i) peptide coupling; (ii) Deprotection with 20% piperidine in DMF; (d) DMF, 5% acetic acid; (e) 4-benzyl lithium oxazolidinone, THF, R4-Z; (f) TFA.
The resin-bound aryl silane intermediate 3-Scheme 6 is prepared using the general procedure outlined above for preparing 2a-Scheme 4. using optionally substituted phthalic anhydride, wherein the optional substituent(s) is Y', and Y' is hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (- NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmeth-oxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl). Additional synthetic chemistry known in the art is performed with eventual preparation of an N-protected amino acid (preferably with an Fmoc protecting group) compound. Peptide coupling is completed using well known published procedures. As used herein, substituent R3 is hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyamino-carbonyl, cyano, nitro (-NO2), aryl, heteroaryl arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl). Deprotection of 4-Scheme 6 is accomplished with conventional techniques (such as 20% piperidine in DMF) to produce 5-Scheme 6. Cyclization of 5-Scheme 6 is accomplished with an organic acid (such as acetic acid) in an aprotic solvent (such as DMF) to produce 6-Scheme 6. Analogs of 6-Scheme 6 may be N-alkylated at the position- 1 nitrogen of the benzodiazepine ring (depicted in the scheme as R4), using conventional techniques, for example, reaction with a base (such as 4-benzyl lithium oxazolidinone) in an aprotic solvent and alkylation with an alkyl halide or alkyl tosylate (such as R4-Z, wherein R4 is alkyl; and Z is Br, I or tosylate). Cleavage of the resin-bound aryl silane intermediate 7-Scheme 6 to produce an optionally substituted aromatic carbocycle, i.e., the benzodiazepine &z Scheme 6. is accomplished by treatment with strong acid.
For purposes of illustration for this scheme, X is Br and A, B and C are hydrogen. However, it will be recognized that further diversity may be placed on the end-product benzodiazepine if the substituents X, A, B and C on the staring material are as defined more broadly, above.
Scheme 6a
Using the alternative synthetic sequence depicted below, 4b-Scheme 6 may be synthesized through a nitrobenzophenone intermediate.
Figure imgf000035_0001
Figure imgf000035_0002
(a) n-BuLi, THF, 2-nitrobenzoyl chloride; (b) NaSH, THF, MeOH/water
Scheme 7
Scheme 7 illustrates a method for preparing 1,3- or 1 ,4-diaminobenzene compounds, one of the various types of aromatic carbocycles that may be prepared using the silane linkers of this invention:
Figure imgf000036_0001
Figure imgf000036_0002
R
Figure imgf000036_0003
NHCOR
S_
(a) n-BuLi, THF, -105°C, BrCH2Si(Me)2Cl; (b) (i) NaOMe, 4-hydroxybenzyl alcohol, THF; (c) NaH, THF, Merrifield chloromethyl resin; (d) (i) NH3, MeOH; (e) NaSH, THF, Water; (iii) Peptide coupling; (iv) TFA to cleave the aromatic carbocycle while leaving a hydrogen at the cleavage site. In a manner similar to that described in Scheme 1, a substituted silane intermediate of Formula (LLB), (i.e., 2-Scheme 7). wherein R" and R'" are methyl; the substituents X and A are bromine and nitro, respectively; B and C are hydrogen; Y is bromine; and n is 1, is prepared by forming a lithium species of 2,4- dibromonitrobenzene (Aldrich) and subsequent reaction with a silane compound (such as bromomethyl chlorodimethyl silane available from Aldrich) in an aprotic solvent (such as THF or ether). The aryl silane intermediate of Formula (ILB), wherein R" and R'" are methyl; substituents X and A are bromo and nitro, respectively; B and C are hydrogen; Y is bromo; and n is 1 (2-Scheme 7 . is then reacted with a strong base (such as sodium methoxide or potassium carbonate) and an optionally substituted benzyl alcohol in an aprotic solvent (such as THF, dimethyl formamide, dimethyl acetamide or DMSO if sodium methoxide is the base; acetone or ethyl methyl ketone if potassium carbonate is the base) to prepare the aryl silane intermediate of 3-Scheme 7. This intermediate is coupled with a polymer resin (such as Merrifield resin, Wang resin, or any other suitable resin described herein) in an aprotic solvent (such as THF) using a base (such as sodium hydride, sodium methoxide in THF, dimethyl formamide, dimethyl acetamide or DMSO, or potassium carbonate in acetone or ethyl methyl ketone) to produce 4-Scheme 7. Additional synthetic chemistry, such as reduction of a nitro group to an amino group, which will be obvious to one of ordinary skill in the art, is performed in order to modify the substituents X and A. Subsequent additional synthetic chemistry may be performed, such as N-acylation using various carboxylic acid derivatives and amino acids under standard conditions known in the art, to produce N-substituted resin-bound aryl silane intermediates 5-Scheme 6. Cleavage of the resin-bound aryl silane intermediate with strong acid conditions affords 6-Scheme 7. wherein substituents B, C, R5 and R6 are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, t-butoxyaminocarbonyl, cyano, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl).
Scheme 8
Scheme 8 illustrates a method for preparing amino carboxy compounds, another class of aromatic carbocycles that may be prepared using the silane linkers of this invention:
Figure imgf000038_0001
Figure imgf000038_0002
(a) n-BuLi, THF and CO2; (b) peptide coupling; (c) (i) NaSH, THF, Water; (ii) peptide coupling; (iii) TFA, Neat.
In a manner similar to that described above for Scheme 7, resin bound aryl silane intermediate 1 -Scheme 8 is prepared. Additional synthetic chemistry is performed on the intermediate in order to prepare amino carboxy aromatic carbocycles 4-Scheme 8. For example, when the substituent X of 1 -Scheme 8 is bromine, the bromine moiety is converted, by conventional techniques to a carboxy group, through an alkyl lithium species in an aprotic solvent (such as THF). 2c Scheme 8 is converted to an amide using conventional peptide coupling techniques with various amines and amino acid derivatives. Additional synthetic chemistry which would be obvious to the skilled artisan is performed in order to modify the substituents X, A, B and C, for example, N-acylation using various carboxylic acids and amino acids. Cleavage of the modified aromatic carbocycle in order to prepare the final product which is a compound of 4-Scheme 8. wherein the substituents B, C, R7 and R8 are, independently from one another, hydrogen, halogen, alkyl, alkenyl, alkynyl, alkoxy, aryloxy, thioether, alkylthio, C(O)Ra, wherein Ra is hydrogen or alkyl, cyano, t-butoxyaminocarbonyl, nitro (-NO2), aryl, heteroaryl, arylalkyl, alkyl disulfide, aryl disulfide, acetal, fluorenylmethoxycarbonyl or orthoester (-C(OR)3, wherein R is Cj to C4 alkyl), is accomplished under strongly acidic conditions (such as treatment with TFA).
Scheme 9
Scheme 9 illustrates a method for preparing biphenyltetrazole compounds, yet another class of aromatic carbocycles that may be prepared using the silane linkers of this invention.
Figure imgf000040_0001
Figure imgf000040_0002
Figure imgf000040_0003
Figure imgf000040_0004
(a) (i) NaN3, A1C13; (ii) Base, R9Z', wherein Z' is Cl, Br, I or tosylate; (b) n-BuLi, Ether, BrCH2Si(Me)2; (c) (i) NaOMe, 4-hydroxy benzyl alcohol; (ii) NaH, THF, Merrifield chloromethyl resin; (d) (i) Pd(PPh3) , 4-R10-substituted phenylboronic acid [wherein R10 is aldehyde (-CHO), -CH2OR, halogen, -CH(OR)2, -C(OR)3, - NO2, -NR2, -SR, (wherein R is C to C4 alkyl), an ethylene dioxy group, or an optionally substituted aryl group] Na2CO3(aq), toluene, ethanol; (ii) TFA, Neat.
2-Scheme 9 (wherein X and A are bromine and B and C are defined as described above) prepared by reacting 1 -Scheme 9 (prepared from 2,4- dibromobenzoic acid which is available from Aldrich, by reaction with methanesulfonyl chloride and ammonia) with sodium azide in the presence of a Lewis acid, and then N-alkylating the intermediate previously formed, using conventional techniques, for example, reaction with a base (such as NaH, potassium carbonate or trialkylamines) in an aprotic solvent, and alkylation with an alkyl halide or an alkyl tosylate (such as R9-Z', wherein R9 is alkyl; and Z' is Cl, Br, I or tosylate). 2-Scheme 9 is coupled with a silane compound and then with a polymer resin to prepare 4-Scheme 9. as described previously. Additional synthetic chemistry is performed in order to modify the aromatic carbocycle bound to the resin. Cleavage of the substituted aromatic carbocycle is accomplished using strong acid conditions. It will be clear that X and A can be other than bromide and as defined above, provided that X, A, B and C can not all be hydrogen and not all X, A, B and C can be alkyl.
Scheme 10 Scheme 10 illustrates the preparation of an aromatic carbocycle 3-Scheme
10. wherein the carbocycle is an aldehyde substituted biphenyl compound. J^ Scheme 10 is prepared according to Scheme 1 and then reacted with an optionally substituted boronic acid (such as 4-formylphenylboronic acid) in a basic medium (such as sodium carbonate) and an aprotic solvent (such as toluene) at elevated temperatures (such as 100°C) to give a resin-bound aryl silane intermediate 2c Scheme 10. Cleavage of 2-Scheme 10 with TFA yields the aromatic carbocycle with a hydrogen at the clevage site.
Figure imgf000042_0001
a) 4-formylphenylboronic acid,( PJi P) Pd, NajCQ (aq), Toluene, EtOH, 100° b) TFA, neat, 25°
Scheme 11
Scheme 11 illustrates the preparation of an amine substituted biphenyl compound using the resin-bound aryl silane intermediate 1 -Scheme 11 (prepared according to step (a) of Scheme 10 above) as a starting material. 1 -Scheme 11 is reacted with an optionally substituted primary amine (such as benzyl amine, Aldrich ®, Milwauke, WI ) in an aprotic or protic solvent (such as toluene, methylene chloride, ethanol or methanol) to give a resin-bound aryl silane intermediate substituted with a benzyl imine (2-Scheme 11). Suitably, the optionally substituted primary amine is substituted with alkyl, aryl heteroaryl, arylalkyl or heteroarylalkyl; preferably arylalkyl; more preferably, benzyl. Additional synthetic chemistry, specifically a Grignard reaction using allylmagnesium bromide (made conventionally) in an aprotic solvent (such as ether and toluene), is performed on resin-bound aryl silane intermediate 2-Scheme 11 to convert the benzyl imine to 3^ Scheme 11. an aminobenzyl substituted alkenyl moiety. Compounds analogous to 3-Scheme 11. but wherein the alkenyl moiety is varied, may be prepared prepared by using a different Grignard reagent under the same reaction conditions. Standard cleavage conditions are used to give 4-Scheme 11.
Figure imgf000043_0001
Figure imgf000043_0002
a) PhC4 NH 2 i Toluene ; b) Allylmagnesium bromide^EO, Toluene, 25°; c) TFA (neat)
Scheme 12
Scheme 12 illustrates the preparation of another substituted biphenyl compound using the resin-bound aryl silane intermediate 1 -Scheme 12 (prepared according to step (a) of Scheme 10 above) as a starting material. In this case, the aldehyde substituted resin-bound aryl silane intermediate 1 -Scheme 12 is reacted with an optionally substituted Wittig reagent (such as phosphorane or a compound of the formula Ph P=CHCOORb, wherein Rb is C\ to Cg alkyl, specifically ethyl) in an aprotic solvent (such as THF, ether or dioxane) at elevated temperatures (such as 60°C) to give resin-bound aryl silane intermediate 2-Scheme 12. The vinyl ester 2c scheme 12 is modified to a thiol addition moiety by reaction with an optionally substituted thiol (such as thiophenol, Aldrich) in a tertiary amine base (such as triethylamine) in an aprotic or protic solvent (such as toluene or ethanol) to give resin-bound aryl silane intermeidate 3-Scheme 12. which intermediate is cleaved to give the desired derivatized aromatic carbocycle, 4-Scheme 12. It will be recognized that various additional synthetic chemistry can be performed on intermediate 2c Scheme 12 in order to derivatize across the alkenyl bond, for example by performing a Wadsworth-Emmons reaction as disclosed by Patios, Tet. Lett., p. 1317 (1991); Coatrot, Synthesis, p. 790 (1956); Marshall, J. Org. Chem., 51(10), p. 1735 (1986); and Mandai, Tet. Lett, 21 pp. 2987-2990 (1992).
Figure imgf000045_0001
Figure imgf000045_0002
a) Phj P=CHCOOEt, THF, 60°; b) PhSH, EN, Toluene, 25° ; c) TFA, Neat
Schemes 13a and 13b
Schemes 13a and 13b illustrate other types of additional synthetic chemistry which are compatible with the aryl silane bond of various resin-bound aryl silane intermediates.
Figure imgf000046_0001
Scheme 13 a a) TFA, Neat
Figure imgf000046_0002
a) PhSH, E| N, Toluene; b) TFA, Neat
Scheme 14
Scheme 14 merely illustrates the standard reaction conditions for making dibromobenzonitrile (starting material 1 -Scheme 15).
Figure imgf000047_0001
Schemes 15 and 16
Scheme 15 illustrates the reaction conditions for making a cyano, bromo- substituted aryl silane compound 4-Scheme 15. Scheme 16 illustrates the preparation of a resin 2-Scheme 16. starting from the Merrifield chloromethyl resin 1 -Scheme 16.
Figure imgf000048_0001
Figure imgf000048_0002
Scheme 15 a) n-BuLi, THF, -105°,BrCHSi( e^CI; b) NaOAc, DMF, 50° c) HCl (3 N), MeOH, 25"
Figure imgf000048_0003
Scheme 16
a) i<e COj , DMF, hydroquinone, 60°
Scheme 17
Scheme 17 illustrates the preparation of a cyano-substituted aromatic carbocycle using the cyano, bromo-substituted aryl silane compound 2-Scheme 17 (prepared per Scheme 15) and resin 1 -Scheme 17 (prepared per Scheme 16) as starting materials. As used herein, "Ph3P" is triphenylphosphine (Aldrich); "DEAD" is diethylazodicarboxylate (Aldrich); and "NMM" is N-methyl moφholine (Aldrich).
Figure imgf000049_0001
Figure imgf000049_0002
Figure imgf000049_0003
a) PrjiP, DEAD, NMM, 35° b) 4-formylphenylboronic acid, £Pfi)4Pd, Na. CQ (aq) EtOH, Toluene, 100° It will be recognized that when the silane linker contains benzylic groups, these groups may be cleaved under acidic conditions, such as with TFA. With respect to chemical transformations of increased complexity, cleavage of the benzylic groups could lead to undesired side products. When preparing a combinatorial library, these side products are particularly undesireable. Therefore, the instant invention includes a silane linker of formula D-CH2-Si-R"R"\ wherein D is -(CH2)3-, i.e., -(CH2)4-Si-R"R'M, as an appropriate silane linker to carry out solid phase synthesis of increasing complexity, particularly when the possibility of undesired side products upon cleavage of the final product from the resin-bound aryl silane intermediate, exists.
Scheme 18
Scheme 18 illustrates the preparation of a resin-bound aryl silane intermediate 3-Scheme 18. utilizing an all carbon silane linker of formula D-CH -Si- R"R'", wherein D is -(CH2)3-, i.e., -(CH2)4-Si-R"R'", wherein R" and R'" are each methyl.
Figure imgf000050_0001
Reagents and Conditions: a) allylmagnesiumbromide, toluene, 90°C PtCI2(PhCH=CH2)2, Toluene
Figure imgf000050_0002
Scheme 18(a) Scheme 18(a) illustrates the preparation of 2-Scheme 18(a) which is a reagent used in the preparation of 3-Scheme 18. described above.
Figure imgf000051_0001
Reagents and Conditions: a) n-BuLi, THF, -78°C; CI(Me)2SiH
Scheme 19
Scheme 19 illustrates the preparation of a sulfonamide aromatic carbocycle ., 1 -Scheme 19) as the starting material.
Figure imgf000051_0002
Figure imgf000051_0003
Figure imgf000051_0004
Figure imgf000051_0005
Figure imgf000051_0006
Reagents and Conditions: a) 4-formylphenylboronic acid, (Ph3P)4Pd, Na C03, EtOH, Toluene, 90°C; b)PhCH2NH2, Toluene, 70°C;
Figure imgf000051_0007
d)TsCI, Pyridine e)TFA:DMS:H20 Scheme 20
Scheme 20 illustrates the use of an acid labile MOM protecting group with the all carbon silane linker. The usefullness of this reaction scheme is the demonstartion that 10% TFA is useful in deprotecting 2-Scheme 20. however, 10% TFA does not cleave the aromatic carbocycle from the resin-bound aryl silane intermediate 3-Scheme 20.
Figure imgf000052_0001
OMOM
Reagents and Conditions:
Figure imgf000052_0002
B(OH)2 . Pd(Ph3P)4, Na2C03, EtOH, Toluene, 90°C; b) 10% TFA in CH2CI2
Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. The following examples further illustrate the synthesis and use of the compounds of this invention. The following examples are, therefore, to be construed as merely illustrative and not a limitation of the scope of the present invention in any way.
EXAMPLES;
Preparation of 4-bromophenyldimethylsilylmethylbromide (2-Scheme 1)
A solution of n-butyllithium (2.5M, 53 mL, 0.133 mole) was added dropwise over
30 minutes under argon to a solution of 1,4-dibromobenzene (30.0 g, 0.127 mole) in dry THF (575 mL) at -78°C. After stirring for 1.5 h, bromomethylchlorodimethylsilane (25.0 g, 0.133 mole) was added to the reaction mixture through a canula and the solution was stirred for 1.5 h at -78°C. The reaction was poured into water (325 mL) and extracted with ether. The combined extracts were washed with water and brine, and then dried (Na2SO4) and concentrated in vacuo to an oil. The oil was distilled (Kugelrohr, 110-125°C, .05 mm Hg) to afford the compound as a clear, colorless oil (22.6 g, 58%). 1H NMR (400 MHz, CDC13) 7.45 (dd, 4H), 2.60 (s, 2H), 0.45 (s, 6H). Preparation of 4-(4-bromophenyldimethylsilylmethyloxy)benzyl alcohol (Formula 3-Scheme 1)
Sodium methoxide (4.17 g, 73.4 mmole) was added under argon to a solution of 4- hydroxybenzyl alcohol (8.67 g, 69.9 mmol) in dry DMF (70 mL) and the reaction mixture was stirred for 30 minutes at room temperature. 4- Bromophenyldimethylsilylmethyl-bromide (22.6 g, 73.4 mmol) was added through a canula and the reaction was stirred at RT for 30 minutes and at 65°C for 45 minutes. The reaction was poured into ice water (250 mL) and extracted with ethyl acetate. The combined extracts were washed with water, 5% sodium bicarbonate and brine and the dried (Na SO4). The solution was concentrated to an oil at reduced pressure and purified by flash chromatography (silica gel, 20% ethyl acetate/hexane) to yield the product as a clear, colorless oil (9.23 g, 38%). lH NMR (400 MHz, CDCI3) 7.48 (dd, 4H), 7.10 (dd, 4H), 4.61 (s, 2H), 3.77 (s, 2H), 0.42 (s, 6H). Preparation of resin-bound aryl silane intermediate 4-Scheme 1 A solution of 4-(4-bromophenyldimethylsilylmethyloxy)benzyl alcohol (7.22 g, 20.55 mmol) in dry THF (5 mL) was added to a suspension of sodium hydride (95%, 0.617 g, 25.69 mmol) and stirred at 30°C until gas evolution ceased. Merrifield resin (Nova Biochem., 1.4 mmol/g)) was added with additional dry THF (15 mL) and the reaction mixture was stirred at 65 to 70°C for 24 h. The reaction mixture was cooled to room temperature and quenched with methanol (5 mL) and the resin was filtered and washed with methanol, mefhanol/water (1:1), methanol, methylene chloride and finally methanol. The product was dried in vacuo for 24 h to yield the title compound (8.99 g). Anal, found: C, 82.20; H, 7.03; Br, 6.67. Preparation of Formula 2-Scheme 2
Wang resin (2.0 g), prepared pursuant to Su-Sun Wang, JACS, 95, p. 1328 (1973), is suspended in THF(15 mL) and allowed to swell for 30 minutes. Sodium hydride(250 mg) was then added in one portion and stirred at room temperature for 2h. Dibromide (2 g) was added, followed by tetra-n-butylammonium iodide and heated under reflux for 4 days. The reaction mixture was cooled and carefully quenched with the addition of methanol (5 mL). Filtration followed by washing with methanol, water, methylene chloride and finally with methanol yielded the resin which was dried in vacuum oven. Anal.: Br (4.7%), MS(DCI, NH3) 380; 349 and 351 peaks equal intensity. Bromination of resin-bound aryl silane intermediate 4-Scheme 1 (See Scheme
3(b))
Resin-bound aryl silane intermediate 4-Scheme 1 (0.5 g) was swelled in methylene chloride(5 mL). Bromine(0.1 mL) was added and stirred overnight. Reaction mixture, after filtering, washing with ether and removal of solvents in vacuo, gave an oil (175 mg) which solidified on standing. It was found to be dibromobenzene by l NMR and m. pt.
*H NMR (CDC13, 400 MHz) d 7.35(s); m. pt. 86-88°C. Reaction of resin-bound aryl silane intermediate 4-Scheme 1 with HBr (See Scheme 3(c))
Resin-bound aryl silane intermediate 4-Scheme 1 (500 mg) was suspended in methylene chloride (5 mL). Gaseous HBr was then passed through the suspension cooled in an ice bath for 5 minutes. The cooling bath was removed and the reaction mixture stirred for 30 minutes. Excess HBr was purged from the suspension by passing Argon until no HBr was detected with pH paper. The resin was filtered off, washed with ether and the solvents removed in vacuo to give 230 mg of an oil. MPLC (silica, ethyl acetate: hexane 1:10) provided the product. MS (DCI, NH3) 428 (M+ +NH4). Reaction resin-bound aryl silane intermediate 4-Scheme 1 with trifluoroacetic acid (See Scheme 3(a))
Resin-bound aryl silane intermediate 4-Scheme 1 (500 mg) was stirred in trifluoroacetic acid (2 mL) and the product was analyzed by GC(SE-30, 50°C) room temperature 5.14 minutes. The formation of bromobenzene was confirmed by co- injection with authentic bromobenzene. Preparation of resin-bound aryl silane intermediate 2a-Scheme 4
A solution of n-butyllithium (1.6M, 4.0 mL, 6.4 mmole) was added dropwise to a suspension of the resin-bound aryl silane intermediate 4-Scheme 1 (2.0 g, 2 mmole) in dry THF (22 mL) at 10°C and the suspension was stirred for 2.5 h at room temperature. Phthalic anhydride (1.18 g, 8 mmol) dissolved in warm THF (6 mL) was added and the suspension was stirred for 1 h at RT. The resin was filtered and washed with THF, THF/water (2: 1), THF/2N HCl (3:1), THF/water (2: 1), water, THF/water (2: 1), THF and methanol. The product was dried in vacuo for 24 h at 50°C to yield the title compound (1.91 g). Anal, found: C, 85.47; H, 7.32. IR (KBr) 1718 cnr1 and 1698 cm-1 (carbonyl stretch). Preparation of resin-bound aryl silane intermediate 2b-Scheme 4
In the same manner as described for resin-bound aryl silane intermediate 2a-Scheme 4, the resin-bound aryl silane intermediate 4-Scheme 1 (0.5 g, 0.5 mmole) in dry THF (6 mL) was treated with a solution of n-butyllithium (1.6M, 1.0 mL, 1.6 mmole) followed by solid carbon dioxide to give the carboxy resin-bound aryl silane intermediate 2b (0.277 g). Anal, found: C, 85.65; H, 7.55. IR (KBr) 1694 cm"1 (carbonyl stretch).
Preparation of resin-bound aryl silane intermediate 2c-Scheme 4 In the same manner as described for resin-bound aryl silane intermediate 2a-Scheme 4, the resin-bound aryl silane intermediate 4-Scheme 1 (0.5 g, 0.5 mmole) in dry THF (6 mL) was treated with a solution of n-butyllithium (1.6M, 1.0 mL, 1.6 mmole) followed by diethyl oxalate (0.34 mL, 2.5 mmol) to give the glyoxylic ester resin-bound aryl silane intermediate 2c (0.330 g). Anal, found: C, 85.75; H, 7.53. IR (KBr) 1735 cm"1 and 1685 cm"1 (carbonyl stretch). Palladium coupling of resin-bound aryl silane intermediate 4-Scheme 1 with phenylboronic acid and cleavage with TFA to produce biphenyl (See Scheme 5) Resin-bound aryl silane intermediate 4-Scheme 1 (2 g) was suspended in toluene (15 mL) and allowed to swell for 30 minutes. To this was added tetrkistriphenylphosphine (275 mg, 0.25 mmol), phenylboronic acid (500 mg, 4.1 mmol), ethanol (2 mL), sodium carbonate, aq (2 mL, 2M), all of which was heated in an oil bath maintained at 90° for 16h. The reaction mixture was cooled, filtered washed with methanol, water, methylene chloride and methanol to give a black solid which was taken for the next step. A portion of the above resin (1 g) was treated with trifluoroacetic acid ( 3 mL) and stirred at room temperature for 24 h. Methylene chloride (10 mL) was added and filtered, washed with methylene chloride. Removal of solvents gave a slight brown oil which was triturated with hexane (50 mL). Evaporation of the hexanes yielded biphenyl (78 mg) which was compared with an authentic sample. Reaction of resin-bound aryl silane intermediate 2a-Scheme 4 lalso 3-Scheme 61 with diphenylphosphoryl azide to prepare 4-Scheme 6
The resin-bound aryl silane intermediate 2a-Scheme 4 was suspended in toluene and allowed to swell for 30 minutes. To this was added diphenylphosphoryl azide and the mixture is heated in an oil bath maintained at 90°C for 16 h. The reaction mixture was cooled and filtered, washed with methanol, methylene chloride, methanol and finally dried in vacuo to give the isocyanate. IR 2100 cm-1.
Hydrolysis of resin-bound aryl silane intermediate Formula 4-Scheme 6 in order to prepare resin-bound aryl silane intermediate Formula 5-Scheme 6 The resin-bound aryl silane intermediate obtained above [4-Scheme 6] was suspended in dioxane and refluxed with aqueous sodium hydroxide overnight. Filtration followed by washing with methanol, water, methylene chloride and finally methanol provided the free amine. Coupling of amino acid with resin-bound aryl silane intermediate Formula 5- Scheme 6 to prepare resin-bound aryl silane intermediate Formula 6-Scheme 6 The amine resin-bound aryl silane intermediate 5-Scheme 6 was suspended in DMF and allowed to react with FMOC-amino acid fluoride in the presence of 4-methyl- 2,6-di-tert-butylpyridine overnight. The resin-bound aryl silane intermediate was filtered, washed with methanol, DMF, methylene chloride and methanol. Drying in vacuo yielded the coupled product.
Deprotection and Cvclization of resin-bound aryl silane intermediate Formula 6-Scheme 6 to prepare resin-bound aryl silane intermediate Formula 7-Scheme 6 The above resin-bound aryl silane intermediate 6-Scheme 6 was suspended in DMF and allowed to react with piperidine to give the free amine. The reaction mixture was filtered and washed as usual to provide the resin-bound aryl silane intermediate free amine. The resin-bound aryl silane intermediate free amine was suspended in DMF and heated at 60° with 5% acetic acid to provide the cyclic product. See, Bunin, B.A., Ellman, J.A., JACS, p. 10997 (1992).
Preparation of the nitrobenzophenone resin-bound aryl silane intermediate (3- Scheme 6)
1 -Scheme 1 (1.0 g, 1.0 mmol) was suspended in THF (10 mL) and cooled to -78°C. Added n-BuLi (1.6 M in Hexanes, 1.6 mmol) and allowed to react for 2 h. The mixture was warmed to -65°C; 2-nitrobenzoyl chloride (1 mL, 7 mmol) was added, and the mixture was allowed to warm to room temperature overnight. Filtration followed by washing with methanol (3x25 mL), water (2x25 mL, methylene chloride (2x25 mL and finally with methanol (50 mL) gave the resin which was dried at 60°C in vacuo. Recovered ( l.Og). IR 1740, 1520 cm"1. Preparation of the aminobenzophenone resin (4-Scheme 6)
A mixture of nitrobenzophenone resin, 3-Scheme 6. (950 mg), NaSH (1.0 g) in THF (10 mL), MeOH (5 mL), water (5 mL) was heated in an oil bath at 70°C for 16 h. The mixture was cooled, filtered and washed with methanol, water, methylene chloride and finally with methanol. Drying at 60°( in vacuo gave a slight yellow resin. Recovered (900 mg). IR 1640 (broad).
Preparation of 4-formylbiphenylsilane resin (2-Scheme 10) The bromoresin 1-Scheme 10 ( lg, 1 mmol) was swelled in toluene (10 mL) and ethanol (4 mL). To this was added 4-formylphenylboronic acid (450 mg, 3 mmol), aqueous sodium carbonate (2 M, 3 mL, 6 mmol) and tetrakistriphenylphosphine palladium ( 200 mg). The reaction mixture was heated under Argon ("Ar") with stirring for 24 h., cooled and filtered through a sintered glass funnel. Washed the resin with methylene chloride, methanol, methanol-water (1:1), methanol, methylene chloride and finally with methanol. Dried in vacuo to give colorless 4- formvlbiphenvl resin 2-Scheme 10. IR (KBr) 1701 cm"1 (CHO). Preparation of the Imine (2-Scheme 11) The resin aldehvdel-Scheme 11 made as described above (250 mg) and benzyl amine (1 mL) in toluene (5 mL) was stirred at 25°C for 12 h. It was then briefly heated for 5 min at 60°C, cooled, filtered and washed with toluene followed by diethyl ether. Dried in vacuo to give 2-Scheme 11 as a colorless solid. IR (KBr) 1643 cm-1 (C=N). Anal C (87.64), H(7.48), N(0.99). Addition of allylmagnesium bromide to 2-Scheme 11 to give (3-Scheme 11) 2-Scheme 11 (250 mg) was swelled in 1:1 ether, toluene (4 mL). To this at 25°C was added allyl magnesium bromide, a conventionally made Grignard reagent, (lmL, 1M in ether) and stirred overnight. Filtered, washed with ether, toluene and finally with ether. Dried in vacuo to give a colorless resin. IR (KBr) 1640 cm-1 (C=C).
TFA cleavage of Amine (4-Scheme 11)
3-Scheme 11 (100 mg) was stirred with trifluoroacetic acid (2 mL) for 12 h., filtered and washed with methanol. Removal of solvents in vacuo followed by stirring with saturated sodium carbonate and extracting into ether provided the biphenyl derivative 4-Scheme 11.
1 HNMR (CDC13, 400 MHz) 57.2-7.8 (m, 14 H), 5.7 (m, 1H), 5.1 (m, 2H), 3.5-3.8
(m, 3 H), 2.5 (bs, 2H). MS (M+H) 314.
Preparation of the Wittig adduct (2-Scheme 12)
Aldehyde resin 1-Scheme 12 prepared as above for 2-Scheme 10 (210 mg) was swelled in THF (3 mL), added phosphorane (350 mg) and heated in an oil bath maintained at 60°C for 24 hr. Cooled, filtered, washed with methanol, methylene chloride and finally with methanol. Dried in vacuo to give a colorless resin 2ι Scheme 12. FT-IR (KBr) 1708, 1636 cm-1. Addition of thiophenol. Preparation of the sulfide (3-Scheme 12) The ester resin 2-Scheme 12 (200 mg) was swelled in THF (3 mL) added triethylamine (0.2 mL) and thiophenol (0.3 mL) and stirred at 25°C for 2 days. Filtered, washed with methanol, methylene chloride and finally methanol. Drying in vacuo provided a colorless solid 3-Scheme 12. FT-IR (KBr) 1735 cm-1. Anal C
84.75, H 7.21, S 2.11.
Cleavage of biphenylsulfide by TFA (4-Scheme 12)
3-Scheme 12 (20 mg) was taken up in a small test tube and exposed to TFA vapors in a dessicator for 24 h. Excess TFA was removed in vacuo and the product extracted into diethyl ether. Removal of solvents provided the sulfide 4-Scheme 12.
MS (M+H) 363.
TFA Cleavage of the ester (2a-Scheme 13a)
2-Scheme 12 (40 mg) was taken in a test tube and exposed to TFA vapors in a dessicator for 24 h. Excess TFA from the resin was removed in vacuo and the product extracted into ether. Removal of solvents provided 2a-Scheme 13a which was found to be pure by 1 HNMR (CDCI3, 400 MHz)
Addition of triphenylphosphoranilidine acetone to aldehyde (lb- Scheme 13a)
1-Scheme 12 was swelled in THF (10 mL) and added phosphorane (1.4 g) and heated at 60° for 24 h. Cooled, filltered and washed with MeOH, CH2Cl2 and finally with MeOH.
Dried in vacuo to provide the ketone.
FT-IR
Preparation of the dibromoamide (2-Scheme 14) To a solution of dibromobenzoic acid (21.6 g, 77.2 mmol) in dry pyridine (150 mL) under Ar was added methanesulfonyl chloride (9.28 g, 81 mmol) and stirred at 0°C for 1 h. To this reaction mixture was passed ammonia gas for 10 min at 0°, and then poured into ice cold water (750 mL). The solid was filtered, washed with water. Air dried to give the amide (15.9 g, 74%). IR (neat) 3366, 3185, 1650 cm-1. 1 HNMR (CDC13, 400 Mhz) δ 7.72 (d, 1H,J= 3Hz), 7.48 (d, IH, J= 7Hz), 7.42 (dd, IH, J= 3,
7 Hz).
Preparation of the nitrile (3-Scheme 14)
To a solution of DMF (3.3 mL, 42.4 mmol) in dry CH3CN (100 mL) at 0°C was added dropwise oxalyl chloride (3.6 mL, 40.8 mmol) over 5 min. After stirring for 5 min at 0°C, a solution of the amide (5.58 g, 20 mmol) in dry DMF (30 mL) was added via canula. After 5 min, pyridine (6.5 mL, 80 mmol) was added over 1 min and the reaction mixture was stirred at 0°C for 15 min. It was then poured into saturated NH4C 200 mL), extracted with 1:1 ethyl acetate: hexane (300 mL). The organic layer was washed with water (2x100 mL), brine (75 mL) and dried over anhydrous Na2SO4. Removal of solvents followed by trituration with hexane provided 3-Scheme 14 (4.68 g, 90%). IR (Neat) 2225, 1570, 1256 cm-1. 1 HNMR (CDC13, 400 MHz) δ 7.75 (d, IH, J= 2 Hz), 7.58 (dd, IH, J= 2, 7 Hz), 7.55(d, IH, J=
7Hz).
Preparation of the bromocvanosilane (2-Scheme 15)
To a solution of 3-Scheme 14 (5 g, 19.2 mmol) in dry THF (200 mL) at -105°C was added under Ar, n-BuLi ( 1.6 M in hexane, 12 mL, 19.2 mmol) over a period of 30 min. The reaction mixture was then stirred for 10 min at -105°C. To this was added bromomethylchlorodimethyl silane (4.67 mL, 24.9 mmol) over 2 min and stirred for 45 min while warming to -80°C. The reaction mixture was poured to water (200 mL), extracted with 1:1 ether: hexane (200 mL), washed with water, brine and dried over anhydrous sodium sulfate. The resuling oil was flash chromatographed (silica, ethyl acetate(3%) in hexane) to give the 2- Scheme 15 (5.01 g, 79%). 1 HNMR (CDC13, 400 MHz) d 7.9 (d, IH, J= 2Hz), 7.75 (dd, IH, J= 2, 7 Hz), 7.5 (d, IH, J= 7 Hz), 2.8 (s, 2H), 0.5 (s, 6 H). Preparation of the Acetate (3-Scheme 15) To a solution of the 2-Scheme 15 (5.01 g, 15 mmol) in dry DMF (50 mL) was added anhydrous sodium acetate (3.70 g, 45.1 mmol) and stirred at 55°C for 16 h. Cooled, poured into ice water, extracted with 1: 1 hexane, ether, wsahed with water, brine and dried over anhydrous Na2SO Removal of solvents followed by flash chromatography ( silica, ethyl acetae: hexane 1: 19) gave the 3-Scheme 15 ( 3.42 g, 73 %). 1 HNMR (CDC13, 400 MHz) δ 7.85 (d, IH, J= 2Hz), 7.75 (dd, J= 2, 7 Hz), 7.5 (d, IH, J= 7 Hz), 4.1 (s, 3H), 2.0 (s, 2H), 0.5 (s, 6 H). Preparation of the alcohol (4-Scheme 15)
To a solution of the 3-Scheme 15 (0.79 g, 2.53 mmol) in methanol (20 mL) was added HCl (3 N, 4 mL) and stirred for 12 h. The reaction mixture was neutralized by the addition of solid sodium bicarbonate, filtered and solvents evaporated. Diluted with ethyl acetae, washed with water, brine, dried. Removal of solvents gave an oil (0.68 g, 100%). IR(neat) 3421, 2226, 1570, 1254 cm-1. 1HNMR (CDC13, 400 MHz) δ 7.85 (d, IH, J= 2Hz), 7.72 (dd, IH, J= 2, 7 Hz), 7.55 (d, IH, j= 7 Hz), 3.75 (s, 2 H), 0.5 (s, 6 H). Preparation of the phenol resin (2-Scheme 16)
To a suspension of Merrifield chloromethyl rein (20 g, 24.8 mmol) in dry DMF (200 mL) was added hydroquinone (21.84 g, 198 mmol) followed by soilid K2CO3 (15.44 g, 112 mmol). The reaction mixture was heated in an oil bath maintained at 65°C for 48 h., cooled, added ethanol (40 mL) followed by gradual addition of 2: 1 EtOH: 3N HCl. The resin was filtered, washed with ethanol, ethanol:3N HCl,
EtOH, THF, MeOH, water, THF and finally with methanol. Dried in vacuo to give 2-Scheme 15 (20.8 g). IR (KBr) 3544, 3429, 1196, 1025 cm-1. Anal: C (89.55), H
(7.31), Cl (0.20).
Mitsunobu coupling of phenol resin (3-Scheme 17)
To a solution of the alcohol (1 g, 3.7 mmol) in N-methylmorpholine (5 mL) at 0°C was added triphenylphosphine (0.971 g, 3.7 mmol) and stirred for 5 min. To this was then added dropwise diethylazodicarboxylate (0.58 mL, 3.7 mmol) and stirred at 0° for 30 min. The resin (1 g, 1.24 mmol) was added, temperature increased to 35. After 4 days, the product was filtered, washed with THF, MeOH and dried at 50° in vacuo to give 3-Schemel7 (1.023 g). IR 2225 cm"1 (CN) Preparation of butenyl polystyrene (2-Scheme 18)
To chloromethyl polystyrene (12.0 g, 2 mmol/gm, 1% cross linked) in toluene (200 mL) was added allylmagnesium bromide (50 mL, 1M in diethyl ether). The reaction mixture was agitated by bubbling Argon through the solution and heated in an oil bath maintained at 90° C for 16 h. Cooled, added saturated ammonium chloride and stirred for 30 min. The resin was filtered, washed with water, methanol and dichloromethane.
Preparation of the resin-bound aryl silane intermediate (3-Scheme 18) To butenyl resin (2 g) in toluene (15 mL) was added bisstyrenylplatinum(II) chloride (200 mg) and 4-bromophenyldimethylsilane (2 g). The reaction mixture was agitated by bubbling Argon through the solution and heated in an oil bath maintained at 95°C for 16 h. The reaction mixture was cooled, resin was filtered, washed with dichloromethane to give the product as a black material.
1 HNMR (MAS, Varian, 400 Mhz) d 7.45 (s, 2H), 7.25 (s, 2H), 2.4(bs, 2 H), 0.5 (s,
2H), 0.1 (s, 6H). Preparation of the biphenylcarboxaldehyde via Suzuki Reaction (2-Scheme 19) To resin-bound aryl silane intermediate (3-Scheme 18. i.e., 1-Scheme 19) ( 2g, 4 mmol) in toluene(30 mL) was added tetrakistriphenylphosphinepalladium (300 mg) followed by 4-formylphenylboronic acid (1.2 g, 8 mmol), ethanol (8 mL) and sodium carbonate (aq, 2 molar, 8 mL). The reaction mixture was agitated by bubbling Argon through the solution and heated in an oil bath maintained at 95 °C for 16 h. Cooled, washed with dichloromethane, methanol, water, methanol and finally with dichloromethane to give product as a black solid (2.2 g). 1 HNMR (MAS) Preparation of the resin-bound aryl silane imine intermediate (3-Scheme 19) To biphenylcarboxaldehyde resin (1 g) in toluene (10 mL) was added benzyl amine (3mL) and heated to 65°C for 10 h. Cooled, filtered and washed with dichloromethane. The resulting resin-bound aryl silane intermediate (3-Scheme 19) (1.1 g) showed characteristic 1 HNMR(MAS).
Reduction of the imine by sodium triacetoxyborohvdride; Preparation of amine bound resin (4-Scheme 19) To 3-Scheme 19 in dichloromethane was added sodiumtriacetoxyborohydride. The reaction mixture was agitated by bubbling Argon through the solution for 24 h. This was followed by the addition of saturated sodium bicarbonate (5 mL) and further agitation for 2 h. The resin was filtered, washed with water, methanol and dichloromethane. FT-IR (disappearance of peak at 1640 cm-1). Preparation of the resin-bound aryl silane sulfonamide intermediate (5-Scheme 19}
To the resin-bound aryl silane intermediate 4-Scheme 19 in pyridine was added p- toluenesulfonyl chloride and agitated by bubbling Argon through the reaction mixture for 24 h. The resin was filtered, washed with dichloromethane, methanol and dichloromethane to provide the resin-bound aryl silane intermediate 5-Scheme 19 as a blackish material. 1 HNMR (MAS). Cleavage of the resin-bound aryl silane sulfonamide intermediate (6-Scheme
121
The resin-bound aryl silane intermediate 5-Scheme 19 was treated with TFA:DMS:H2θ (90:5:5) for 16 h. The solvents were removed under vacuo to provide a pale yellow oil which was compared with an authentic sample prepared earlier.
Synthesis of MOM-protected biphenyl resin-bound aryl silane intermediate (2-
Scheme 20) 2-Scheme 20 was prepared in an analogous manner as of compound 2-Scheme 19.
Characteristic peaks in the 1 HNMR (MAS): d 5.0 (s, 2H), 3.4 (s, 3 H), 0.6 (s, 2H),
0.2 (s, 6 H).
Synthesis of 2-hvdroxybiphenyl linked silane (3-Scheme 20)
To the MOM protected biphenyl resin-bound aryl silane intermediate (2-Scheme 20, 100 mg) was added 10% trifluoroacetic acid in dichloromethane and the reaction mixture was agitated by bubbling Argon through the solution for 8 h. The resin was filtered, washed with dichloromethane. 1 HNMR (MAS) analysis indicated the complete disappearance of MOM group. (100 mg).
It will be clear to the skilled artisan that the silicon linkers and silicon based polymer resins of this invention may be used in a variety of combinatorial methods for synthesizing a large number of molecularly diverse compounds, simultaneously.
For example, the instant invention may be applied to (i) the "multi-pin" method described in Geysen et al., Proc. Natl. Acad. Sci. USA., 81, p. 3998 (1984); U.S. Patent 4,708,871 (1987); Geysen et al., Bioorg. Med. Chem. Lett, 3, p.397 (1993); and European Patent 138,855 (1991); (ii) the "tea-bag" approach described in Houghten, R.A., Proc. Natl. Acad. Sci. USA., 82, p. 5131 (1985); and Houghten et al., Nature, 354, p. 84 (1991); and (iii) chemical synthesis on a "chip" described in Fodor et al., Science, 251, p. 767 (1991) and U.S. Patent 5,143,854 (1992).
In addition, the compounds may be screened in assays which have been developed for determining lead compounds as pharmaceutical agents. For reasons of efficiency, the components of the library are screened in groups of multiple compounds. Therefore, once the library of compounds has been synthesized, there must be some method to deconvolute the results of screening such that individual active compounds can be identified. Based upon the disclosure herein, it will be clear to the skilled artisan that there are many methods for deconvolution of the combinatorial library. For example, if the compounds of the library are screened on a solid support, they may be physically segregated so that individual active compounds may be directly selected and identified. In contrast, if the compounds of the library are cleaved from the resin and tested as soluble mixtures, the library may be deconvoluted in an iterative approach, which involves resynthesis of mixtures of decreasing complexity until a single compound is identified, or in a scanning approach, in which the various substituents on the aromatic carbocycle, are evaluated independently and the structure of active compounds are determined deductively. For an explanation of the iterative and scanning approaches to deconvolution of a combinatorial library of compounds, see, for example, Houghten et al., Nature, 354, p. 84 (1991).
Biological Assays:
(I) A representative binding assay is as follows. Other binding assays or functional assays that are known by, or that would be obvious to the skilled artisan, may be performed as well. Tissue containing the appropriate target receptor are homogenized, filtered through cheesecloth and centrifuged at 1500 x g for 10 minutes. The supernatant is decanted and the pellet is resuspended in an appropriate incubation buffer, e.g. 75 mM Tris.HCl, pH 7.4 containing 12.5 mM MgCl and 1.5 mM EDTA. Membranes equivalent to 100 g protein are incubated with 50 pmol radiolabeled receptor ligand and an appropriate amount of the test library mixture in a total volume of 5001 for 1 hr. at 37°C. The binding reaction is terminated by dilution with the addition of 5 mL of cold incubation buffer and the bound tracer is separated from free by filtration on Whatman GF/C filter paper. The filter paper is washed several times with cold incubation buffer and then counted to determine the amount of bound ligand.
Specific binding is defined as the portion of radiolabeled receptor ligand binding which can be completed by a high concentration of unlabeled receptor ligand. The presence of a competing ligand in the library test mixture is evidenced by a reduction in specific binding of the radiolabeled receptor ligand in the presence of the library test mixture.
(II) An additional assay that is effective and extremely useful for testing the aromatic carbocycles prepared according to this invention is disclosed by Lerner et al., Proc. Natl. Acad. Sci. U.S.A., 91(5), pp. 1614-1618 (1994), which is incorporated by reference herein.
The above description fully discloses the invention including preferred embodiments thereof. Modifications and improvements of the embodiments specifically disclosed herein are within the scope of the following claims. Without further elaboration it is believed that one skilled in the art can, using the preceding description, utilize the present invention to its fullest extent. Therefore any examples are to be construed as merely illustrative and not a limitation on the scope of the present invention in any way. The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows.

Claims

/17695What is claimed is:
1. A method for preparing a resin-bound compound, wherein the compound is an aromatic carbocycle comprising an aromatic carbon atom and at least one substituent that is not hydrogen or alkyl, said method comprising the steps of:
(i) attaching the aromatic carbon to a polymeric resin support through a silane linker to give a resin-bound aryl silane intermediate; and
(ii) performing additional synthetic chemistry on the substituent so that the aromatic carbocycle is derivatized.
2. The method of claim 1 wherein the silane linker is -D-CH2-Si-R"R'", and wherein R" and R'" are independently, C\ to Cg alkyl and D is a Cj to C20 alkyl chain optionally having one or more intervening heteroatoms or aryl groups.
3. The method of claim 2 wherein D is -(CH2)3-.
Figure imgf000065_0001
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6147159A (en) * 1998-09-30 2000-11-14 Argonaut Technologies Compositions for organic synthesis on solid phase and methods of using the same
US6416861B1 (en) 1999-02-16 2002-07-09 Northwestern University Organosilicon compounds and uses thereof
US7985882B1 (en) 2002-08-23 2011-07-26 Biotage Ab Compositions for reductive aminations utilizing supported tricarboxyborohydride reagents and methods of using the same

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4933391A (en) * 1989-02-16 1990-06-12 Eastman Kodak Company Functionalized polymers

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4933391A (en) * 1989-02-16 1990-06-12 Eastman Kodak Company Functionalized polymers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See also references of EP0934345A4 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6147159A (en) * 1998-09-30 2000-11-14 Argonaut Technologies Compositions for organic synthesis on solid phase and methods of using the same
US6416861B1 (en) 1999-02-16 2002-07-09 Northwestern University Organosilicon compounds and uses thereof
US7985882B1 (en) 2002-08-23 2011-07-26 Biotage Ab Compositions for reductive aminations utilizing supported tricarboxyborohydride reagents and methods of using the same

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